4 Male gonadal dysfunction

4

Male Gonadal Dysfunction DAVID J. HANDELSMAN RONALD S. SWERDLOFF

In the decade since the investigation of testicular function was last reviewed in this series (Baker and Hudson, 1974), a number of advances in the diagnosis of gonadal disorders has occurred. The purpose of this chapter is to review the clinical and laboratory investigation of male gonadal disorders with an emphasis on the newer laboratory techniques. The testes serve the dual function of providing both an exocrine secretory product, the mature haploid gametes that constitute the male contribution to fertilization, as well as endocrine secretions that exert specific androgenic and diverse anabolic effects on the whole body. The clinical features of testicular dysfunction can be understood as pathological consequences of damage to one or both of the two structurally and functionally distinct but highly interdependent compartments of the testis, namely the Leydig cells and the seminiferous tubules. In this review we will give a brief outline of the current understanding of the normal function of the hypothalamic-pituitary-testicular (HPT) axis which will be elaborated as a framework within which to understand the current state of clinical and laboratory investigations of the basic and specialized investigations in most widespread use for laboratory investigation of male gonadal function. The most common clinical disorder of testicular function leading to medical investigation is male infertility, and the review will reflect this preponderance. Two other areas of clinical disorders of testicular function, namely androgen deficiency (hypogonadism) and impotence, will also be briefly discussed to illustrate specific features of the clinical and laboratory investigations appropriate to each situation. It should be clear, however, that in many instances the pathophysiological disturbances of testicular dysfunction presenting as infertility, androgen deficiency, impotence, delayed or precocious puberty and gynaecomastia will demonstrate similarities. The overlapping clinical features of these disorders reflect the close integration of the steroidogenic and spermatogenic functions of the testis. A common although quite misleading usage has been to refer to testicular dysfunction as hypogonadism only when androgen deficiency is Clinics in Endocrinology and Metabolism-Vol. 14. No. L February 1985

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present and infertility when only spermatogenesis is defective. Since this is well entrenched we shall abide by this convention despite noting its inappropriateness. NORMAL PHYSIOLOGY OF THE HYPOTHALAMIC-PITUITARYTESTICULAR AXIS The testes, under the dominant hormonal control of pituitary gonadotrophin secretion, produce both endocrine (steroidal) and exocrine (spermatozoa) as well as paracrine products (Figure 1). The complex interplay of the finely regulated and multiply redundant control systems governing these integrated functions is only slowly being unravelled. Recent reviews of advances in clinical and experimental studies are available (Burger and De Kretser, 1981; Lipshultz and Howards, 1983). Leydig cells occur as groups of polygonal cells scattered in the intertubular (interstitial) tissues and constitute about 1-10% of total testicular volume. Leydig cells are freely exposed to the extracellular fluids and are principally under the control of pituitary luteinizing hormone (LH). The detailed nature of the regulation of Leydig cell function at the

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subcellular level has been greatly advanced by the development of highly sensitive and specific methods for characterizing LH receptor binding at the Leydig cell surface and the postreceptor intracellular events that follow (Catt et aI, 1980). LH binding to its highly specific membrane receptor causes conformational changes in the receptor and the adjacent membrane, and ultimately these changes induce activation of a cascade of postreceptor events-including increases in intracellular cyclic AMP and GMP levels, increased phosphorylation of intracellular proteins, accelerated membrane phospholipid turnover, and rapid calcium channel flux. The net result of these changes is the activation of the rate-limiting steps of testicular steroidogenesis. The highly specific interaction of LH with its membrane receptor protein also induces changes in the normal turnover of cell surface LH receptors and at other undefined intracellular postreceptor sites that act to limit Leydig cell responses to prolonged or excessive exposure to LH. These coordinate changes include decreases in the number of remaining LH receptors (down-regulation) and sensitivity of the Leydig cell (desensitization) to further stimulation. LH receptor stimulation ultimately leads to increased secretion of testosterone, T, the principal steroidal product of the testis and major androgen in the body. Testosterone is secreted into the blood-stream where it circulates bound to plasma proteins, principally sex-hormone binding globulin (SHBG) , and into the seminiferous tubules where it is bound to androgen-binding protein (ABP) , a Sertoli cell product. The roles of the gonadal and circulating steroid binding proteins are not fully understood, but they modulate androgen actions. The physiologically active androgen moiety has been identified as the non-protein-bound, 'free', testosterone. The SHBG-bound testosterone may function as a reservoir that buffers the 'free' fraction and other steroid-binding proteins with less avid binding, such as albumin and alpha-l acid glycoprotein, serving intermediate roles. Androgen effects are exerted on the appropriate target organs which are distinguished by the presence of the specific, high-affinity androgen receptor protein in the cell cytosol. Biologically active androgens can bind reversibly to the cytosolic androgen receptor with relative affinities that reflect their biopotency as androgens in vivo. Such binding events are followed by transformation of the androgenreceptor complex into an activated state, translocation of the complex into the nucleus and binding to nucleoproteins. The interaction of the activated, nuclear-translocated androgen receptor initiates a cascade of DNA transcription, RNA translation and protein synthesis leading to expression of the characteristic spectrum of effects of androgens on general anabolism and induction of specific androgenic effects in the appropriate target tissues. Although testosterone is the major testicular androgen product, it is converted to an even more potent androgen, dihydrotestosterone (DHT) , by the action of the enzyme 5-alpha-reductase found specifically in many androgen-responsive target tissues (Figure 2). Since the metabolite DHT is several times more potent than testosterone as an androgenic ligand at the androgen receptor, it has been suggested that testosterone is a circulating prohormone for the active androgen , DHT.

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D. J. HANDELSMAN AND R. S. SWERDLOFF

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Figure 2. Mechanism of androgen action at the cellular level. In a majority of androgensensitive cells, testosterone (T) penetrates the plasma membrane and is converted to dihydrotestosterone (DHT) by 5-alpha-reductase. DHT binds to a cytoplasmic androgen receptor and the DHT-receptor complex is translocated to the nucleus. In cells in which 5-alpha-reduction of testosterone occurs to a limited extent, testosterone binds to the receptor and the complex is translocated to the nucleus. Association of the androgen-receptor complex with nuclear acceptors is followed by synthesis of androgen-dependent messenger RNA and proteins. Antiandrogens such as cyproterone acetate inhibit androgen binding to the cytoplasmic receptor. Some actions of testosterone do not require receptor binding.

Tissues embryologically derived from the urogenital sinus (and from which ultimately the external and internal genitalia are formed) are particularly dependent on the actions of DHT as an androgen. Apart from the urogenital tissues which appear more responsive to DHT, the more general anabolic actions of androgens on bone, marrow, muscle, skin and brain are subserved equally well by either DHT or T. Major advances have occurred in the understanding of the regulation of LH secretion over the last decade following the proliferation of radioimmunoassays for LH and the full characterization of the hypothalamic gonadotrophin-releasing hormone (GnRH) in the early 1970s (Knobil, 1980). Peripheral LH levels fluctuate widely as a result of intermittent bursts of pituitary secretion of LH. The intermittent pituitary secretory activity is, in turn, primarily the result of bursts of secretion of endogenous GnRH into the hypothalamic-pituitary portal blood vessels. Pituitary gonadotrophin response to GnRH is determined primarily by the frequency of pulses of GnRH secretion. LH secretion is pulsatile at all stages of life, although the pulse amplitude and frequency vary considerably under a range of physiological circumstances. The most striking pulsatile patterns are observed in adults where the dominant frequency of peripheral LH pulses in normal men is between 60 and 90 minutes per pulse. The GnRH-secreting neurones of the mediobasal hypothalamus are subject to complex regulation by the interplay of negative steroidal

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feedback and both stimulatory and inhibitory neurotransmitter (catecholamine, dopamine, serotonin, acetylcholine) and neuropeptide (endogenous opioid peptides) signals (Kalra and Kalra, 1983). The most wellcharacterized control mechanism for the regulation of the GnRH-secreting neurone is that of the negative feedback by sex steroids. Testosterone feedback in the male interacts with the opioid and neurotransmitter mechanisms of the hypothalamus and all of these influences converge in altering secretion of GnRH into the pituitary portal blood which in turn ultimately influences pituitary gonadotrophin output. Catecholaminesecreting neurones directly stimulate the GnRH-neurones, whereas this trophic influence is modulated by tonic, presynaptic inhibition by neurones secreting endogenous opioid peptides. Hypothalamic regulation of pituitary-gonadal function by the determination of GnRH pulse frequency and amplitude, as well as sensitivity to negative steroidal feedback, is related to both higher neural regulation and external environmental cues. Examples of this higher level of coordination include the influence of malnutrition in causing hypogonadotrophic hypogonadism in males with anorexia nervosa (Wheeler et al, 1983) comparable with that of anorexic females, the altered levels of the feedback setpoint for negative steroidal feedback both prior to puberty (Styne and Grumbach, 1978) and in advancing age (Muta et al, 1981) and the influence of photoperiod and seasons, possibly mediated by the pineal (Reiter, 1980), on male reproductive function. The regulation of spermatogenesis has distinct mechanisms and feedback controls from that of Leydig cell function (Baker et al, 1976). The intimate structural and functional relationships between the two interdependent compartments of the testes are becoming increasingly apparent. The Sertoli cells are the sole target for follicle-stimulating hormone (FSH) action since they possess the only specific, high-affinity FSH cell surface membrane receptors in the testis. Sertoli cells partition the seminiferous tubule into external (basal) and internal (adluminal) compartments by forming tight cell-cell junctions that constitute a blood-testis barrier. All spermatogenic cells are embedded in the highly convoluted cytoplasmic processes of the Sertoli cells which serve nutritive and coordinating functions in the timely sequence of sperm production. Sertoli cells supply both metabolic fuels to the spermatogenic cells and secrete a variety of proteins with presumed regulatory functions in the evolution of differentiated functional haploid gametes. Spermatogenesis requires FSH for its initiation and possibly also for its maintenance. Quantitatively efficient spermatogenesis, however, also requires a high local concentration of testosterone which is dependent on adequate Leydig cell stimulation by LH. Testicular mechanisms to maintain the high local concentrations of androgens include the physical proximity of Leydig cell groups in the interstitium to the seminiferous tubules and the elaboration by Sertoli cells into the seminiferous tubular lumen (adluminal compartment) of an androgen-binding protein (ABP) which maintains high androgen concentrations in the microenvironment of the developing and maturing spermatozoa until they are finally stored in mature form in the caudal

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epididymis. Much work has been expended in the biochemical characterization of the non-steroidal Sertoli cell product, inhibin, for which there is suggestive evidence in a wide range of studies of normal and aberrant gonadal function (Baker et al, 1976; Franchimont et al, 1979). Current understanding suggests that decreases in spermatogenesis are accompanied by decreased Sertoli cell inhibin production, and this reduction in negative feedback is associated with a reciprocal elevation of FSH levels. Thus isolated elevations of circulating FSH constitute an important and sensitive marker of the state of germinal epithelial activity for clinical diagnostic purposes. CLINICAL ASPECTS The clinical history and examination remain the most important diagnostic tools in the evaluation of male gonadal dysfunction. Rational and efficient use of laboratory investigations depends on a focused differential diagnosis and clear definition of what information is being sought from laboratory tests. The evaluation of infertility, androgen deficiency, impotence and pubertal failure will be dealt with separately to illustrate the common aetiologies and diagnostic considerations. Male infertility (Tables 1 and 2) The prevalence and mechanisms of male infertility remain poorly understood. Fertilization is a time-dependent stochastic process that can proceed only if a number of integrated physiological processes in both the male and female function normally. Infertility is therefore defined in relationship to a particular couple. The creation of a viable embryo requires that the male supply a sufficient number of sperm with adequate

Table l. Causes of male infertility and hypogonadism. Pre-testicular Hypothalamic H ypogonadotrophic hypogonadism (GnRH deficiency) congenital - without or with anosmia (Kallman's syndrome) acquired - trauma - infiltrative disease (sarcoid, tuberculosis, fungal) - malnutrition (anorexia nervosa) - systemic disease (uraemia, liver failure) Exogenous hormones and hormone-like drugs androgens and anti-androgens oestrogens and anti-oestrogens progestins glucocorticoids drugs (cimetidine, spironolactone, digoxin) Functional hyperprolactinaemia (hypothalamic dopamine deficiency) - drug-induced (metoclopramide, tranquillizers, antihypertensives) - idiopathic

MALE GONADAL DYSFUNCTION

Table I contd. Pituitary Pituitary tumour prolactin-secreting (macro- or microadenoma) other hormone or non-secreting tumour Pituitary disease haemochromatosis congenital acquired transfusional iron overload - thalassaemia - other blood disease autoimmune hypophysitis

Testicular Chromosomal disorders Klinefelter's syndrome (47 XXY) autosomal and sex-chromosomal translocations ? other autosomal and sex-chromosomal polyploidies Developmental disorders prenatal DES syndrome cryptorchidism (uni- or bilateral) torsion varicocele Orchitis mumps other viral orchitis tuberculosis leprosy (lepromatous) Immunological disorders autoimmune orchitis (rare) isolated associated with organ-specific autoimmune cluster disease (adrenal, thyroid) sperm antibodies Therapeutic drugs alklyating agents cytotoxics non-alkylating drugs nitrofurantoin antibiotics aminoglycosides cimetidine others spironolactone - sulphosalazine Irradiation ionizing radiation (x-rays, gamma radiation) microwave radiation Testicular toxins - alcohol social intoxicants - tobacco - THC - opiates pesticides and insecticides occupational toxins dibromochloropropane (DBCP) chlordecone (Kepone) ? carbamates heavy metals lead cadmium carbon disulphide cotton-seed oil (gossypol)

95

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D . J . HANDELSMAN AND R. S. SWERDLOFF

Table I contd. Biosynthetic defects in androgen synthesis congenital acquired Myotonic dystrophy Paraplegia

Post-testicular Ductular system congenital aplasia of vas deferens , epididymes and seminal vesicles isolated or associated with cystic fibrosis uni- or bilateral prenatal DES syndrome acq uired Young's syndrome surgical vasectomy inadvertent during inguinoscrotal surgery (herniorrhaphy, orchiopexy, varico- or hydrocelectomy, vasography, renal allograft) infections gonorrhoea non-specific urethritis tuberculosis Disorders of sperm function congenital immotile cilia syndrome (including Kartagener's syndrome) acq uired sperm antibodies drugs varicocele accessory gland infection Dis orders of androgen action congenital 5-alpha reductase deficiency androgen receptor deficiency or dysfunction acq uired ? drugs ? other effects

Table 2. Clini cal evaluation of male infertility .

History Fertility status duration of infertility fertility history Female factors o vulatio n status tub al status general health

-

primary versus secondary contraceptive usage results of previous investigations

-

? spontaneous or induced , ? regular monitor ing method (sympto ms, thermal shift, midluteal pr oge sterone) laparoscopy or hysterosalpingogram medi cations and/or illnesses exercise and diet patterns

-

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Table 2 contd. Androgenic status and sexual function shaving frequency temporal and body hair pattern libido and potency intercourse pattern-timing and technique Past medical history recent illnesses or operations any chronic medical or surgical illnesses Medications alcohol tobacco non-prescribed medications therapeutic drugs treatments for infertility Developmental history pubertal timing history of cryptorchidism or torsion Trauma injuries operations infertility tests-testicular biopsy or vasography incidental inguinoscrotal surgery-herniorrhaphy, hydrocelectomy, orchidopexy Infection genitourinary-mumps, orchitis, NSU, gonorrhoea, other STD sinopulmonary---ehronic sinopulmonary infections

Examination General physical examination height, weight nutritional state blood pressure skin colouration midline cranial malformations and olfaction Androgen status general appearance skin voice musculature proportions ('1 eunuchoidal) gynaecomastia body fat distribution body hair distribution temporal recession axillary and pubic hair (Tanner stages) facial hair chest and abdominal hair Genital penile development (size, hypospadias) scrotal development and contents (testicular or epididymal cysts, malformations, varicocele, hydrocele, hernia) testicular size (Prader orchidometer) testicular consistency (atrophic softening)

fertilizing capacity and the ability to arrive at the distal end of the Fallopian tube at an appropriate time to fertilize a mature oocyte. In addition, the creation of a viable embryo will lead to an ongoing pregnancy only if

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D. J. HANDELSMAN AND R. S. SWERDLOFF

Fallopian tubal and endometrial function are adequate to sustain nidation. A failure of anyone or more of these steps can lead to absolute or relative infertility in a couple. In the minority of infertile couples where the man demonstrates a total barrier to fertilization (e.g., bilateral orchidectomy, persistent complete necro- or azoospermia or immotile sperm), male infertility can be considered absolute. This is usually irreversible, although in some instances (e.g. obstructive azoospermia) treatment is possible. Infertile couples with absolute and irreversible male infertility should be given sympathetic counselling to recognize the futility of further therapeutic interventions and instead such couples should consider alternative family formations such as adoption or artificial insemination by donor sperm (AID). Professional psychological counselling may need to be considered for some couples in whom the impact of the diagnosis of infertility can induce a major bereavement-like reaction. The physician should also review the patient for evidence of hypoandrogenism since severe, irreversible seminiferous tubular failure (azoospermia, small testes [<8 ml], elevated FSH) may be accompanied by various degrees of Leydig cell failure and androgen deficiency (see below). If hypoandrogenism is present, the patient should be given androgen replacement therapy, understanding clearly that androgen replacement therapy cannot restore fertility. In all other couples where even a few viable sperm are present in the ejaculate, male infertility can be considered only relative (Swerdloff and Boyers, 1982). Since clinical testing of each of the steps necessary for fertilization in any particular infertile couple is not possible, it is often difficult to be certain whether only one or more defects are contributing to the couple's infertility; consequently, the contributions of male and female partners to a couple's infertility cannot always be fully distinguished. This is most obvious in couples with unexplained infertility which is diagnosed by exclusion when all conventional tests in the infertile male and female (semen analysis, ovulation, tubal patency, cervical mucus function, sperm antibody testing) are normal. In these couples, as well as in some men with oligospermia, it is likely that defects in sperm function, especially in their fertilizing capacity, are important. The critical threshold level for the number of functionally normal sperm required to reach and fertilize a mature oocyte are probably quite low. Studies of men treated with male contraceptives or cytotoxic drugs have indicated that very low numbers of sperm (as low as 1-2 million/ml) can produce a pregnancy. Since many infertile men have sperm numbers well in excess of these thresholds, it is likely that deficient sperm function (particularly in fertilizing capacity) is instrumental in causing infertility. The clinical study of human sperm fertilizing capacity has recently been advanced by the development of a variety of clinical tests of sperm function, including objective measures of motility, penetration of cervical mucus, and homologous and heterologous fertilization assays. Consequently, in the evaluation of men for infertility, the rationale aim should be to search for any absolute causes of infertility and then determine whether quantitative or qualitative abnormalities of

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sperm numbers and function are present and what associated disorders might be present. In the couple presenting for evaluation of infertility clinical examination and basic testing of the male should be completed before any invasive investigations of the female are considered, unless concurrent evaluation indicates that a female problem is likely. The patient's past fertility history and investigations provide a unique opportunity to assess his actual reproductive performance and fertilizing capacity over a period of time. The duration of infertility in the current relationship should be obtained by considering both the duration of known involuntary infertility as well as periods of unrecognized infertility including periods of unreliable contraceptive usage. Previous instances of conception with the same or another partner, either before or during the current relationship, may indicate the existence of normal sperm fertilizing capacity at one time and help localize the obstacles to fertilization in both time and as to differential fertility in the partners. Clearly this information should be sought in a sensitive and discreet manner respecting its confidential nature. The general medical history should focus on prior or current medical illness or surgical procedures. Recent illnesses, particularly those associated with weight loss and/or fever or for which medication is prescribed, should be carefully detailed. Febrile viral or bacterial illness within the last three months of sufficient severity to require bed-rest or interruption of work may be an important cause of a temporary decline in semen quality and detailed evaluation for infertility should be deferred. Androgenic status can be inferred from the maintenance of libido, potency and shaving frequency. Sexual function should be investigated as to whether both the technique and timing of intercourse are appropriate for achieving fertilization. Developmental disorders of the testis that should be sought include cryptorchidism, torsion or prenatal diethylstilbestrol (DES) syndrome (Whitehead and Leiter, 1981). The age of onset and the rate of evolution of puberty is best gauged by referral to contemporaneous events such as age at leaving school and the relative development of peers. Often the details of the developmental history may need to be obtained with the patient's help in contacting parents and previous medical attendants if these are available. Findings of epididymal cysts and a history of maternal medication for repeated abortion is particularly suggestive of the prenatal DES syndrome. Similarly a history of repeated visits to the family doctor in early childhood, especially if injections were given, might suggest a history of cryptorchidism. An increasingly large range of testicular toxins have been recognized in the workplace and in medical and domestic environments recently. The medical history should therefore include a careful account of all medications (including social intoxicants and non-prescribed medicines) and an occupational history (including hobbies and pastimes). Therapeutic drugs (especially alkylating agents) and irradiation administered for malignant disease or immunosuppression are well-known causes of testicular damage (Ash, 1980; Schilsky et al, 1980). Among the diseases for which treatment is

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administered with therapeutic rather than simply palliative intent are the common malignancies of the male reproductive age-group , namely testicular tumours and lymphomas. Combination cytotoxic regimes are associated with outcomes that vary from virtually no recovery of normal spermatogenesis after ten years following MOPP chemotherapy for Hodgkin's disease (Waxman et al , 1982; Whitehead et al , 1982) to nearly complete recovery within a few years after testicular irradiation (Ash , 1980; Hahn et al, 1982; Handelsman and Turtle, 1983) . Testicular toxicity is both dose- and regime-dependent, and the deleterious effects of irradiation and chemotherapy on the testis are markedly potentiating. Dose fractionation increases the testicular toxicity of irradiation but the equivalent effects of cytotoxic drug dose fractionation are not known. Other medications associated with testicular dysfunction include cimetidine (Carlson et al, 1981), sulphasalazine (Birnie et al, 1981), nitrofurantoin, anticonvulsants, tranquillizers and various androgens or other sex steroids (Wilson and Griffin, 1980). Antihypertensive agents are also frequently associated with erectile or ejaculatory failure. Environmental toxins indentified with testicular damage include consumption of all the social intoxicants (alcohol, tobacco, THC, opiates) . High doses of ethanol are associated with direct testicular toxicity as well as indirect effects in causing liver disease (Boyden and Pamenter, 1983). Similarly smoking is associated with reductions in sperm output and function (Shaarawy and Mahmoud, 1982; Handelsman et ai, 1984b). The impact of THC (tetrahydrocannabinol) and opiate use on human testicular function are less clear since studies showing marginal deleterious effects did not exclude the influence of concurrent malnutrition and multiple drug usage on the testis. The full occupational history should include the nature of materials (including fumes and chemicals) handled or to which he is exposed both at the workplace and at home. Over recent years a range of testicular toxins has been identified through infertility case identification rather than by drug surveillance agencies. An increasing number of other compounds are being identified as testicular toxins, and careful evaluation of cases among infertile males is likely to uncover more in the future . Genitourinary infections have a variable relationship to testicular dysfunction (Fowler, 1981). Epididymo-orchitis , particularly that due to mumps, is clearly a cause of hypogonadism and infertility. Mumps only rarely causes orchitis before puberty and, even after puberty, orchitis is unilateral in about half of all clinically overt cases with subsequent atrophy in less than half of testes that undergo orchitis (Lambert, 1951). Other causes of genitourinary infection, including the sexually transmitted diseases and non-specific urethritis , have a controversial relationship with male infertility due to putative effects on sperm function, but lower genitourinary infections do not cause testicular dysfunction per se. A history of chronic sinopulmonary infections may suggest the diagnosis of Young's syndrome , immotile cilia syndrome or cystic fibrosis (Handelsman et ai, 1984a). Surgical and non-surgical trauma rarely leads to scarring and mechanical obstruction of the sperm outflow tract by fibrous adhesions. Unrecognized

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damage to one or both vas deferens, especially following childhood inguinoscrotal surgery, should be suspected if a history of such surgery and high titres of sperm antibodies in serum are found. Accidental trauma to the testis is frequently recalled by patients during clinical interview but is rarely of importance in the aetiology of testicular disease. Physical examination of men presenting for evaluation of testicular function should include evaluation of signs of concurrent or underlying medical disease, evidence of chronic androgen deficiency and abnormalities in the size or consistency of the testes and accessory scrotal structures (epididymis, vas deferens). Signs of chronic sinopulmonary infections, liver or renal disease, peripheral neuropathy or other features of general ill-health should be noted. Chronic androgen deficiency is suggested by features such as eunuchoidal proportions, gynaecomastia or immature patterns of distributions of body fat, muscular development, beard and body hair growth, decreased sebum production and excessive facial wrinkling or poor genital development. After the time of onset of expected puberty, the use of Tanner staging of pubic hair and genital development should be employed to determine the relative progress of puberty. Longitudinal patterns within the same individual are sensitive markers of the progress of normal hypothalamic-pituitary-testicular axis evolution. Testicular size should be determined by comparison of testicular size with the use of a Prader orchidometer consisting of a series of moulded plastic ellipsoids graded in size from 1 to 30 rnl. Normal values for testicular volume are greater than 15 ml. The use of calipers or punched-out shapes are considerably less accurate or sensitive to alterations in testicular size for reasons of technical facility and geometry. In addition to palpation ofthe testes, the routine examination of men for testicular dysfunction should include examination of scrotal accessory glands (epididymis, vas deferens) and prostate. Scarring or tenderness suggests a chronic infection and possible ductal obstruction whereas unilateral or segmental agenesis of the vas deferens may be diagnosed. Epididymal obstruction often is associated with palpable, non-tender and smooth cystic dilatation of the caput (Handelsman et al , 1984a). Varicocele can be detected after examination of the patient while standing when the hydrostatic filling of the venous varicosities makes the diagnosis most reliable. In the presence of delayed puberty and/or chronic hypoandrogenism, the findings of anosmia or mid-line facial malformations may provide the diagnosis of Kallman's syndrome (Lieblich et al, 1982). Androgen deficiency and resistance Androgen deficiency in the adult male may be due either to direct damage to the testis and Leydig cells (primary, hypergonadotrophic hypogonadism) or, indirectly, to dysfunction of the hypothalamus and pituitary (secondary, hypogonadotrophic hypogonadism). These states are distinguished biochemically since the lowered testosterone levels are accompanied by elevated LH levels in primary hypogonadism but normal to low levels of LH in secondary hypogonadism. Primary hypogonadism may also be

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associated with grades of androgen deficiency from frank hypoandrogenism (low testosterone, elevated LH) to compensated Leydig cell failure (normal testosterone, elevated LH). In addition, androgen deficiency at either testicular or cerebral level may be either congenital or acquired in origin. The causes are listed in Table 1. Androgen resistance is due to structural or functional defects of the cytosolic androgen receptor in the peripheral androgen-sensitive tissues (Griffin and Wilson, 1980). The biochemical features include the concurrent elevation of both LH and testosterone. Congenital androgen resistance is associated with a range of clinical defects, from complete feminization of the external genitalia (complete androgen insensitivity, testicular feminization) to various grades of perineoscrotal hypospadias following the failure of prenatal androgen exposure. Postnatal or acquired androgen resistance may be manifested merely as disturbance in spermatogenesis or sperm function with little or no phenotypic abnormalities (Aiman et al, 1979). Normal exposure of the male to androgens at prenatal, postnatal prepubertal and adult phases produces characteristic features of normal male physiology, and conversely chronic deficiency of androgen at each stage results in typical clinical stigmata of hypogonadism. Prenatal androgen supply is crucial in the formation of morphologically normal external genitalia and defects of phallic, scrotal or urethral development indicate prenatal hypoandrogenism. Postnatal prepubertal androgen deficiency is characteristically associated with abnormal body growth, development and composition. Typical features of juvenile hypoandrogenism include disturbed pubertal progression, eunuchoidal proportions, underdeveloped musculature, larynx, sebaceous glands, body hair patterns and altered body fat deposition. Loss of androgen exposure in the adult is associated with regression of normal secondary sexual characteristics (genital, body hair pattern, muscles), gynaecomastia, skin pallor, excessive facial wrinkling and hot flushes. In subjects being evaluated for testicular dysfunction the evaluation of the pattern of signs of androgen deficiency can give some indications of the onset and nature of the underlying disorders. The current clinical state of testicular androgenic supply can be inferred from the features that require androgen for normal function. These include the maintenance of libido and potency, body hair distribution including beard growth rate, pattern of axillary, pubic and body hair and temporal hair loss as well as the general anabolic state of muscle, bone and skin. Unfortunately the threshold level of androgenic supply required for these bodily functions is low and, furthermore, each has many other determinants related in complex fashion. This makes the clinical signs and symptoms of hypogonadism late features of chronic androgen deficiency. Conversely, normality of these features is a necessary but not sufficient criterion for the clinical diagnosis of normal androgen production. In some instances, especially where compensated Leydig cell failure (normal testosterone, elevated LH) is present and the evidence of overt androgen deficiency is equivocal, a three-month trial of androgen replacement with observation of suitable clinical and biochemical end-points may help

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determine whether any benefit may be attached to institution of long-term androgen replacement therapy. Replacement regimes of androgen should be administered at a dose rate of at least 200 mg of testosterone esters per 10-14 days in view of the poorly sustained testosterone levels (Snyder and Lawrence, 1980; Sokol et aI, 1982). Biochemical testing can help confirm deficient Leydig cell function. In the basal state, total and free testosterone levels are low while SHBG levels are often elevated. As noted, LH (and usually FSH) levels are elevated in primary and low-normal in secondary hypogonadism. In primary hypogonadism,LH mean levels and pulsatility are increased whereas the testosterone response to HCG stimulation is abnormally low or absent. In secondary hypogonadism, testicular testosterone response to HCG is usually normal while LH mean levels and pulse patterns in the basal state are damped or absent but may be primed with repetitive GnRH stimulation (in the case of hypothalamic GnRH deficiency) or remain unresponsive (in pituitary damage). Total and free testosterone levels as well as a variety of peripheral markers of androgen action (haemoglobin, urea, creatinine, SHBG, thyroxine binding globulin) can be used to follow the progress of androgen replacement therapy regimes (Palacios et aI, 1983). Androgen resistance is diagnosed by the combination of biochemical evidence of simultaneous elevation of LH and testosterone levels and confirmation of defective androgen receptor numbers or function ill tissue culture of genital skin fibroblasts. Impotence Impotence is traditionally considered with problems relating to testicular function because of the intimate connection between a threshold level of androgen supply and normal sexual function. In fact modern studies have confirmed the rarity of androgen deficiency as a frequent cause of impotence in otherwise healthy men. The diagnosis and management of impotence has advanced considerably as a result of the widespread implementation of the multidisciplinary approach to evaluation and treatment of erectile failure (Wagner and Green, 1981). Comprehensive profiles are obtained of the patient's psychological state, underlying medical problems, drug and alcohol history, and hormonal profile (basal LH, FSH, testosterone, prolactin), evaluation for neurological and vascular disease, and recordings of nocturnal penile tumescence (NPT) in a sleep laboratory are made. These studies together allow precise delineation of men with psychogenic from those with organic impotence since the former demonstrate preservation of reflex REM-associated erections. Using these modern techniques the proportion of men with organic impotence, once thought to be less than 10%, has been estimated to be as high as 50% (Spark et aI, 1980). In the evaluation of men with impotence, a full sexual history detailing the nature of the sexual dysfunction, the degree of retention of libido, the rate of onset and specificity of the symptoms for particular partners or situations should be clarified. An insidious onset of progressively failing

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potency with loss of spontaneous morning erections but preservation of libido is suggestive of an organic type of impotence. The existence of underlying medical illness-such as diabetes, hypertension , chronic liver disease , alcoholism or other drug usage (antihypertensive, tranquillizers, metoclopramide , cimetidine), chronic renal failure , temporal lobe epilepsy or signs of peripheral neuropathy, or loss of peripheral pulses-support the diagnosis of organic impotence. Conversely, the abrupt onset of impotence selective for specific situations accompanied by preservation of spontaneous erections is indicative of psychogenic impotence. It should be noted , however, that the classification into psychogenic and organic categories is oversimplified in that erectile failure of any type is often accompanied by various degrees of psychological upset. A careful psychological assessment as part of the multidisciplinary approach should clarify the mechanism and distinguish secondary overlays. The clinical distinction into psychogenic and organic impotence is usually but not always confirmed by NPT testing. Men with psychogenic erectile failure are usually amenable to the application of psychotherapy and behaviour modification. In the case of men with organic impotence, the application of nerve conduction, penile blood flow studies and angiography can differentiate between neurological and vascular aetiologies. In a few instances of vascular steal syndromes (including the Leriche syndrome), microvascular surgery may improve penile blood flow sufficiently to restore erectile function (Wagner and Green , 1981). In most other instances, the only possible therapy for severely impaired erectile capacity is the insertion of a penile prosthesis. Advances in the technology of penile prostheses, such as the development of inflatable devices, has made this option more attractive; however, the long-term results and side-effects of these devices, particularly in younger men, have yet to be fully evaluated. LABORATORY INVESTIGATIONS

Laboratory investigations of testicular function can be divided into basic tests that are widely available and good screening tests for testicular dysfunction. These include semen analysis and measurements of basal FSH, LH and testosterone . More specialized tests are applicable to isolate specific abnormalities in selected patients. These include dynamic tests of the HPT axis, other more specialized hormonal assays, immunological and paternity tests, tests of functional or fertilizing capacity of human sperm, cytogenetic tests, semen biochemistry, testicular biopsy, contrast radiography and nocturnal penile tumescence monitoring. The subsequent discussion will reflect this clinical approach to diagnosis. In any patient being investigated for a potential testicular disorder, the basic tests should be completed as far as possible before deciding whether to proceed on to other more sophisticated tests . The pattern of specialized investigations will differ, however, according to the patient's needs and the nature of the presenting complaint.

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Basic tests

Semen analysis Semen analysis is a valuable test of the quality of germinal epithelial function of the testis. Although semen analysis is often restricted to men undergoing evaluation for infertility , it should be obtained whenever possible in men undergoing study of testicular function since normal values are strong evidence against testicular dysfunction. Ideally three specimens should be analysed at least one month apart to indicate the nature of spermatogenesis over a time period that covers approximately the generation time of human sperm (about 74 days). Semen samples should be collected by masturbation into a clean plastic container, the timeinterval from last ejaculation noted, and the sample examined within a short time interval (less than 1 hour) from collection. This is most easily arranged with the use of a suitable collection room within the same building as the semen laboratory. Semen collected through interrupted intercourse, with or without the use of condoms, is less satisfactory in view of loss of the sperm-rich first fraction of the ejaculate and the inadvertent admixture of toxic lubricants, rubber products or acid vaginal secretions. Specimens should be examined by an experienced technician and the semen volume , sperm density, motility (and forward progression grading) and percentage of morphologically normal oval-shaped spermatozoa in a stained smear should be reported as described in the standard World Health Organization (WHO) reference manual (Belsey et ai , 1980).

Basal hormones Blood should usually be collected at the first opportunity for measurement of basal levels of FSH , LH and testosterone. A single sample of 5-10 ml whole blood , collected at a standard time of day to minimize diurnal variation (usually morning) , is usually adequate for this purpose. In some instances, collection of multiple samples (typically three collected through an indwelling cannula a t 20-minute intervals) may be assayed as a single sample consisting of a pool of equal aliquots from each time-point. The extra time in collection and processing of samples is balanced by the value of obtaining a more integrated measure of basal hormone secretion since secretion of both gonadotrophins is intermittent rather than continuous. In cases of borderline elevations of gonadotrophins, a second set of samples should be collected on a different day. , The proliferation of radioimmunoassay kits for measurement of FSH, LH and testosterone has greatly increased the availability of these assays but has also introduced problems of assay standardization and betweenassay quality control. A wide variety of standards for radioimmunoassays of LH and FSH continues to be employed. These standards, purified to various degrees from pituitaries or urine , are heterogeneous in biological and immunological properties, and the use of different standards can lead to wide discrepancies between various centres in the 'normal' ranges. International Standards for Radioimmunoassay of LH (68/40) and FSH

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(69/104) assays recommended by the World Health Organization are distributed by the Medical Research Council of the UK; however, most kits use less well-defined secondary standards. To alleviate these problems of both bias and imprecision, laboratories employing radioimmunoassay for diagnostic purposes should have rigorous in-house, quality-control (QC) procedures open to scrutiny by the referring clinician, and preferably should take part in external QC programmes on a national or international basis as well. Furthermore, the temptation to change assay procedures or kits for reasons of expense or convenience should be resisted without careful attention to the effect of such changes on assay utility in baseline and follow-up studies of patients. In gonadotrophin assays, the lower 95% confidence limits of the LH and FSH levels in normal subjects often extend down as far as the valid detection limits of the assay. Since 'low' levels of gonadotrophin are undefined, the diagnosis of gonadotrophin deficiency cannot be made reliably with basal gonadotrophin measurements alone. Thus the clinical application of gonadotrophin assays is primarily to detect elevation of LH and FSH. Ideally then, the point of maximum assay precision according to the precision profile should be situated, by appropriate optimization of the assay, to lie in the region of the upper limit of normal range. It is important to remember that gonadal hormone levels are clearly related to age, general health and the quality of spermatogenesis. Consequently normal ranges should be determined from healthy men in specific age-groups where the quality of spermatogenesis is controlled, and not from random sampling of convenient volunteers or blood donors.

Interpretation of basic tests (Table 3) Interpretation of the results of any clinical assay depends on the comparison of an analytically valid assay result from an individual with a statistically valid reference range, conventionally a 95% confidence Table 3. Interpretation of clinical evaluation and basic test.

Persistent azoospermia (1) Severe irreversible seminiferous tubular failure FSH - high Testis size - small «8 ml) Prognosis very poor for recovery Advise - counselling - adoption - AID - trial androgen replacement (2) Obstruction FSH - normal Testis size - normal (>15 ml) Advise - bilateral testicular biopsies and scrotal exploration (only if bypass is considered) - recommend bypass surgery only if spermatogenesis is normal, the scrotal vas deferens is infact and the couple understand the low likelihood of success after epididymal obstruction

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Table 3 coned.

(3) Cytotoxic effects FSH - high Testis size - normal or slightly reduced (> 12 ml) Advise - serial monitoring of FSH at 4-6-month intervals - progressive fall in FSH levels indicates a good prognosis for recovery of spermatogenesis - failure of FSH to fall over a prolonged period indicates a poor prognosis. Treat as for (1) above (4) Idiopathic germinal cell damage FSH - normal or only slightly elevated Testis size - reduced «15 ml) Advise - testicular biopsy appearance is invariably either that of late stage maturation arrest or hypospermatogenesis. Almost certainly a heterogeneous group of disorders with common final histopathological manifestations. Prognosis poor and no specific therapy available. - test for sperm antibodies. If positive at high titres, consider immunosuppressive treatment for autoimmune orchitis - otherwise treat as in (1) except that empirical therapies (see below) may be considered Persistent oligospermia (sperm density < 10 millionlml) FSH - high Advise - germinal epithelial damage - treat as in (3) above. If serial FSH levels fall, spermatogenic recovery is expected; if no fall treat as (1)

FSH Advise

-

normal or only slight elevation sperm function assay (motility, cervical mucus interaction tests, heterologous or homologous fertilization assays). If normal results, prognosis good; if results abnormal, consider empirical treatments empirical treatments varicocele ligation scrotal cooling gonadotrophin stimulation (HCG) anti-oestrogens (clomiphene, tamoxifen) testosterone rebound aromatase inhibitors (teslac)

A bnormal sperm function Low motility, immotile or non-viable sperm Poor penetration of cervical mucus Low rate of in vitro fertilization Advise - no specific therapies available - exclude or treat causes of possible underlying testicular or epididymal dysfunction e.g., sperm antibodies, genitourinary infection, varicocele - if disorder of sperm function is persistent, consider referral for artificial insemination by donor sperm

interval, based on an unbiased sample of the normal population. Such information concerning semen analysis is not available since semen analyses have generally been available only from non-random samples of men biased with respect to their fertility status since they are ascertained because of infertility or prevasectomy screening. Surveys of presumed fertile or presumed infertile men indicate that the ranges of semen analyses are very wide, skewed and highly overlapping in these two select groups. Since the general male population consists of many men with unknown

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fertility in addition to those presumed fertile or infertile , it is likely that population normal range spans at least the upper and lower limits defined in the biased samples of men with defined fertility . This would suggest that a current best estimate of 95% confidence intervals for sperm density in the normal population are 10-250 million sperm/ml (Macleod and Wang, 1979; James , 1980; Handelsman et al , 1984b). The term oligospermia , which means a sperm count below the range in normal men, should therefore be restricted to men with sperm densities inferior to 10 million/ml until more accurate estimates of spermatogenesis in normal men are available. The creation of a semantic disease by describing men as 'oligospe rmic' when sperm density falls below a set level, ranging from 10 to 60 million sperm/ml, determined from various unrepresentative samples of normal men , is not meaningful. Motility is the most important single parameter of sperm function that can be assessed from semen analysis. Abnormal motility can consist of completely non-motile sperm due to either necrospermia or the immotile cilia syndrome (these can be distinguished by sperm vitality staining), or reduced or non-progressive forward motility. The latter is the more common and is attributable to inadequate functional development of sperm in the testes and epididymis . A characteristic 'shaking' vigorous but non-progressive motility is noted in semen specimens from men with high levels of sperm antibodies. Recent developments in the objective measurement of sperm swimming speed by video techniques or laser light scattering suitable for computer-assisted semi-automation (Lee et ai , 1982; Blasco, 1984) make it likely that objective measurement of these parameters can be made available in a practical manner for routine use in the near future. Assessment of sperm morphology provides an indication of the health of the germinal epithelium. Under circumstances when the germinal epithelium undergoes unusually heavy stimulation or toxin exposure , less mature spermatogenic cells are shed prior to completion of spermiation and therefore appear in the ejaculate as incompletely developed forms. This pattern is analogous with the well-known phenomenon of 'left-shift' on blood films under conditions of increased haematopoietic marrow output. Therefore increased numbers of morphologically abnormal sperm in the ejaculate indicate malfunction of the germinal epithelium and possibly functional immaturity of released sperm. Abnormalities attributed to other numerical variations in semen parameters-such as high or low ejaculate volumes, excess ive numbers of sperm or the character or composition of semen, coagulum or its dissolution-have no proven relationship to disorders of fertility. Basal hormone assays can help clarify the cause of testicular dysfunction if semen analysis is abnormal. In azoospermic men about half the cases have markedly elevated FSH levels, indicating severe germinal cell damage. while the others have normal FSH levels that indicate normal spermatogenesis but sperm outflow obstruction of the efferent ducts or epididymis. Elevation of FSH is usually a reliable indicator of germinal epithelial damage presumably due to reduction in Sertoli cell inhibin secretion and feedback on pituitary FSH release. Persistent elevation of

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FSH indicates continuing abnormal seminiferous tubular function, but a falling level indicates recovery of spermatogenesis after toxic damage . Leydig cell function is regulated independently of seminiferous tubular function. Therefore normal or elevated FSH levels may be accompanied by patterns of LH and testosterone secretion that indicate normal Leydig cell function (normal LH and testosterone) or mild (elevated LH, normal testosterone) or frank androgen deficiency (elevated LH, decreased testosterone) due to Leydig cell dysfunction. Most LH and FSH assays cannot reliably distinguish low from normal levels of gonadotrophins, and consequently the diagnosis of gonadotrophin deficiency is made by the finding of low total and/or free testosterone levels in conjunction with low-normal LH levels. The differentiation between gonadotrophin deficiency due to hypothalamic or pituitary dysfunction is facilitated by the multiple-dose GnRH stimulation test. The diagnosis of pituitary gonadotroph damage is supported by a failure of GnRH 'priming' of plasma LH and FSH levels, whereas a marked 'priming' response is suggestive of a defect in hypothalamic GnRH secretion (Snyder et ai, 1979). Prognosis (Table 3) The prognostic importance of semen analysis is related to the numbers of sperm, the vigour and directionality of their motility and the proportion of morphologically normal sperm in the ejaculate. Persistent azoospermia associated with elevation of FSH and small, atrophic testes is associated with an essentially hopeless prognosis for fertility as in the instance of Klinefelter's syndrome. If any element in this triad is missing , however, the prognosis for future fertility must be considered as non-zero. For example, if the semen analysis contains any sperm at all , pregnancy must be considered possible and falling FSH levels are a good prognostic sign. Non-motile sperm are also associated with a very poor prognosis for fertility; however, the prognosis attached to the more common moderate reduction in sperm forwardly-progressive motility is less clear. Oligospermia with sperm density consistently below 10 million per ml is a limitation on fertility potential , and the 'time-to-fertilization' is roughly proportional to sperm density in this range. Among the various parameters of the semen analysis, there is general agreement that determination of the quality of forwardly-progressive motility provides the most important independent prognostic parameter of sperm function and fertilizing capacity.

Specialized tests Dynamic hormonal tests

A variety of dynamic tests is available to determine the physiological state of the HPT axis in men with reproductive dysfunction. These tests are pulsatility studies and stimulation tests with GnRH , HCG and clomiphene. In most instances these give little additional information in a single patient beyond that obtained in basal hormone estimations . Consequently these

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tests are only rarely indicated for individual patients and are used mostly in detailed investigational protocols. It has been known for over a decade that peripheral levels of LH, and to a much lesser extent FSH, undergo periodic abrupt elevations due to an intermittent pituitary secretion of gonadotrophins. Pulsatile secretion appears to be a feature of the regulation of the GnRH-secreting neurones of the mediobasal hypothalamus throughout life, although the nature of the ultimate zeitgeber (time-clock) remains unknown. Although physiological and pharmacological changes are associated with differences in LH pulse amplitude and frequency, there are no specific instances yet described of isolated failure of the pulse generator. Pulse amplitude is usually proportional to overall mean LH concentration, so that in men with primary hypogonadism LH mean levels and pulse amplitude are increased compared with men with normal testicular function. Consequently, objective computer-assisted analysis of LH pulse frequency and amplitude can add information about the operating conditions of the LH pulse generator and in particular its hormonal milieu, but is not diagnostic of any specific disorder. The recognition of the intermittent elevations of LH in all adult men does make repeated determinations of single abnormal results essential, especially with minor elevations. High non-pulsatile LH levels might be present in cases of HCG-secreting tumours. The GnRH stimulation test may be administered as a either a single dose (usually 100 ug) stimulation test or as part of a multiple dose (usually much lower dose, 1-10 ug/dose) priming test (Snyder et al, 1979). The peak responses of LH and FSH to single-dose GnRH stimulation are proportional to the prevailing basal levels and there is little other information obtainable from any other combination of response metameters apart from the peak-to-basal ratio (Harman et al , 1982). Consequently the diagnostic information from a single-dose GnRH stimulation test is only marginally more than that obtained from basal LH and FSH levels. In cases of primary testicular damage, basal and peak gonadotrophin levels are increased whereas in hypothalamic or pituitary disease, basal and peak levels may vary from normal to reduced. One advantage of the single-dose GnRH stimulation test is that a lower limit for LH (but not FSH) can be determined, so that subnormal responses, typically in hypogonadotrophic hypogonadism, can be defined in individual subjects. Low LH responses to single-dose GnRH stimulation, however, do not reliably distinguish between hypothalamic or pituitary disease. The multiple-dose GnRH stimulation test uses the principle of 'priming' the pituitary gonadotrophs by repeated low dose stimulation as is the case under physiological conditions where the pituitary is normally exposed to brief, regularly repeated pulses of GnRH. For example, the multiple-dose GnRH priming test can demonstrate that low or absent LH responses to a single dose of GnRH in hypothalamic disorders can be augmented to give normal LH levels, whereas in pituitary disorders no such priming occurs (Snyder et al, 1982). Leydig cell function is conventionally tested by repeated injections over a period of days with high doses of HCG which normally stimulates a prolonged increase in testicular testosterone output. HCG binds to the

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Leydig cell membrane LH receptor because of the close structural similarity of the biologically active beta subunits of LH and HCG . HCG is employed because of its commercial availability and its conveniently long half-life . Recent animal and human studies have demonstrated that these conventional doses of hCG cause supramaximal stimulation to the Leydig cells (Padron et ai, 1980). Such high doses are associated with profound and prolonged down-regulation (decreases in number) of testicular LH receptors and desensitization of the testis to subsequent doses of HCG/LH . Similar information about the ability of Leydig cells to respond to maximal stimulation with HCG/LH can be obtained with single and substantially lower doses of HCG . As with the pituitary gonadotroph responses to GnRH stimulation, the Leydig cell response to HCG stimulation is dependent on a variety of influences, including its recent exposure to endogenous LH as well as a number of paracrine influences of the seminiferous tubular cells. In addition, the testis has a large reserve capacity to respond to HCG, so that this test is insensitive to mild testicular pathology and only becomes abnormal when other endocrine changes, such as elevation of LH levels, are already apparent. In addition, interpretation is also impaired by the uncertainty whether alterations in Leydig cell responses to HCG are due to disorders intrinsic to the Leydig cells, to associated disorders of the seminiferous tubules , or to the influence of the prevailing levels of circulating LH. Consequently the responses of individual patients to HCG add little new information to diagnosis, and the use of this test is also largely for detailed evaluation of groups of patients under investigational protocols. The major suitable indications for the application of the HCG stimulation test is to exclude anorchia in cryptorchid boys with impalpable testes. The clomiphene test is based on the observation that in normal adult men and men with primary testicular damage , clomiphene administration caused a marked elevation in both LH and FSH . In contrast, in prepubertal boys or men with pituitary or hypothalamic disease clomiphene administration is associated with reduced or absent elevations in LH and FSH . The mechanism of this effect was thought to reflect an inhibition of oestrogenic feedback with a reflex rise in gonadotrophins as a consequence of reduced negative feedback. It was hypothesized that this test was a form of reflex test of the feedback sensitivity of the hypothalamic-pituitary unit . A direct stimulatory effect of this nonsteroidal anti-oestrogen on pituitary gonadotrophs, however, has never been satisfactorily excluded (Adashi, 1984), and the mechanism of action remains uncertain-particularly since the observation of additional, nonoestrogenic clomiphene binding sites in some tissues (Sutherland et al, 1980). The advent of the GnRH priming stimulation test will continue the trend to relegate this rather unsatisfactorily defined test to limited investigational use only. Other hormonal tests In some instances the measurement of other hormones, usually by radioimmunoassay, may contribute further useful diagnostic information.

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In this context measurements of prolactin, alpha-subunit glycoprotein, oestradiol and other oestrogens, dihydrotestosterone (DHT), free levels of testosterone, sex-hormone binding globulin (SHBG), and bioassays of LH and FSH are occasionally useful. Prolactin measurements are of great importance in the diagnosis of prolactin-secreting adenomas of the pituitary (Perryman and Thorner, 1981). Prolactin levels over 200 ng/ml are virtually diagnostic of macroadenoma, whereas levels between 50 and 200 ng/ml are consistent with either structural (macroadenoma, microadenoma) or functional (drug ingestion, renal or hepatic failure) disorders of prolactin regulation. Prolactinomas are much less common in men than in women and most often present with features reflecting their size as space-occupying lesions in the pituitary region (headaches, visual field defects, haemorrhage) or with hormonal features of hyperprolactinaemia (impotence) or general features of chronic hypogonadism (reduction in body hair and testicular size). Suppression of prolactin levels with bromergocryptine therapy is associated with marked reduction in pituitary tumour size and improvement in potency, although testicular function does not improve so readily. Prolactin levels in the range between the upper limit of the normal range (10-15 ng/ml) but under 50 ng/ml are most commonly due to the stress associated with venipuncture or cannulation and typically do not remain elevated during serial sampling or on a repeated sampling at another occasion. Minor elevations of prolactin levels (15-50 ng/ml) are common in men with primary testicular dysfunction, possibly because of oestrogeninduced hyperprolactinaemia since oestradiol levels are elevated in men with hypergonadotrophic hypogonadism. Suppression of minor elevations of prolactin levels (15-50 ng/ml) by administration of bromergocryptine is ineffective in improving depressed spermatogenesis, so that the diagnostic importance of prolactin levels is restricted to marked elevations (>50 ng/ml). Prolactin deficiency is rare and is not a known cause of any reproductive disorders. Alpha-subunits of all four dimeric glycoproteins (HCG, LH, FSH, TSH) hormones are identical within a species, the biological specificity and specific receptor binding properties residing in the beta-subunit. Alphasubunits are normally produced in excess and secreted as monomers into the circulation by the pituitary gland. Higher circulating levels of free alpha-subunits occur when pituitary glycoprotein hormone secretion is increased, as in physiological (ovulatory surges, menopause), pathological (gonadal or thyroidal failure, renal failure, pituitary tumours) or pharmacological (GnRH or TRH stimulation) states. Although such levels of alpha-subunits are without known effect on gonadal function, elevations can indicate states of abnormal pituitary function due to tumour or hyperstimulation, and high levels can induce artefactual elevations of the other glycoprotein hormones due to cross-reactivity of the alpha-subunits in most gonadotrophin radioimmunoassays. Measurement of oestrogens, notably oestradiol, the most potent oestrogen, is of little diagnostic importance in the investigation of testicular dysfunction. In normal men only about 25% of circulating

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oestradiol is secreted directly by the testis, the remainder being derived from peripheral aromatization of testicular androgens (testosterone, androstenedione). The proportion of circulating oestradiol derived from the testis rises after Leydig cell stimulation with either exogenous LHlHCG or endogenous LH in men with testicular damage. Even under these circumstances, only a small fraction of circulating oestradiol reflects Leydig cell function, making it an insensitive marker of testicular function and hence unsuitable for routine use. Oestradiol assays may be helpful in excluding oestrogen-secreting tumours of steroidogenic organs (adrenal, testis) as a cause of gynaecomastia. Measurement of DHT suffers from the same limitations as oestradiol in the diagnosis of testicular disease in that only a small proportion is secreted directly from the testis, the rest being formed in androgen-responsive target tissues (liver, kidney, muscle, prostate, skin) containing the enzyme 5-alpha reductase. Levels of DHT are not usually abnormal in men with testicular disease. However, levels may be low, particularly after hCG stimulation, in the congenital disorder associated with 5-alpha reductase deficiency. Interpretation of these findings is complicated by the observation that dermal 5-alpha reductase is itself an androgen-inducible enzyme. SHBG levels are typically elevated in men with testicular dysfunction resulting in a reduction of the proportion of total circulating testosterone that is 'free' (i.e., not bound to protein) in the circulation. Although it has generally been assumed that unbound testosterone is the metabolically active moiety, the relative availability to the tissues of unbound compared with testosterone bound to high-affinity binding proteins such as SHBG or other proteins with lower affinity such as albumin, transcortin and alpha-l acid glycoprotein remains controversial. SHBG levels can be measured indirectly by a variety of liquid- or solid-phase radioreceptor assays using tritiated DHT as ligand or, more recently, by direct radioimmunoassay of SHBG. Systematic examination of the binding affinity of SHBG by a comparison of levels as measured by radioimmunoassay (reflecting total mass of the protein) to those measured by binding assay (reflecting the affinity of the specific androgen binding site on SHBG) are yet to be reported but may be disturbed in some diseases. SHBG levels are increased in thyrotoxicosis, chronic liver disease and testicular failure, as well as by administration of thyroxine, oestrogens and some drugs. Levels are lowered in obesity, hypothyroidism and after androgen administration. Congenital deficiency of SHBG without reproductive sequelae has been described in one family. Only a small portion of total circulating testosterone is available for biological activity, and this portion has been identified as the non-proteinbound or non-specifically bound androgen. 'Free' testosterone can be measured by the reference method of equilibrium dialysis, assayed directly by radioimmunoassay, calculated from measurements of SHBG levels, or inferred from direct assay of salivary testosterone levels. In most clinical situations, the proportion of testosterone that is 'free' by equilibrium dialysis is inversely related to the SHBG levels. In addition there is a close relationship between total and free testosterone levels. The clinical utility

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of measurement of 'free' testosterone and SHBG is to give more precise information than is available from the basal total testosterone levels. This is most valuable in determining the actual androgenic status when concurrent disorders of the hypothalamus and pituitary alter the interpretation of LH levels or SHBG levels (Glass et al, 1977). Applications of serial measurement of free testosterone and SHBG levels has been useful in monitoring therapeutic responses to different forms of androgen replacement therapy in hypogonadal men (Davidson et al, 1982).

Bioassays of LH and FSH In vitro bioassays for both LH and FSH have been established to facilitate the analysis of gonadotrophin molecular heterogeneity. These bioassays differ from the classical in vivo bioassays of LH and FSH in that the use of tissue culture methods for cellular isolation allows greater economy and precision. LH bioassays are based on the in vitro production of testosterone by Leydig cells isolated from rats, mice or other species. Assay of plasma samples against various gonadotrophin standards has revealed marked variations in the ratio of biological to immunological activity (B/I ratio) of the predominant species of LH molecules secreted under differing physiological conditions. For example, chronic treatment with GnRH analogues or primary hypogonadism are associated with reductions in LH B/I ratios. Disparities between the apparent levels of immunoreactive LH and the circulating levels of testosterone and/or signs of androgen deficiency may be explained by elaboration of an LH molecule of unusually low (or high) biological potency. A case of pubertal failure and hypogonadism associated with a biologically inactive form of LH has been described. In vitro bioassays for FSH are less widely available. However, similar circumstances can be envisaged for the comparison of biological to immunological potency to FSH under circumstances where conventional immunoassay results are discrepant from the clinical condition. For example, isolated elevation of FSH in the presence of normal spermatogenesis may be due to aberrant immunoreactivity (Karpas et al, 1983).

Androgen receptor abnormalities In a limited number of centres, tissue culture of genital skin fibroblasts derived from punch-biopsies can provide tissue to determine the number and biochemical properties of androgen receptors from the individual under study (Griffin and Wilson, 1980). Usually the activity of the androgen-target organ enzyme, 5-alpha reductase, can be measured in the same fibroblasts. Congenital and acquired defects of the steroidogenic enzymes of the testis as well as molecular disorders of the cytosolic androgen receptor have been described and lead to a wide range of disorders of testicular function. Of these disorders the phenotypic expression of androgenic effects are typically defective, although the severity of the hypogonadism varies considerably from complete blockade of all androgenic effects (complete androgen insensitivity; testicular feminization syndrome) to minor disorders involving minimal androgen

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deficiency . The biochemical features of elevated LH levels and accumulation of steroidogenic precursors proximal to the biochemical block in androgen production or expression, as well as determination of androgen receptors and steroidogenic enzyme activity in cultured, biopsied skin fibroblasts, help in the accurate diagnosis of these disorders. It should be noted, however, that acquired androgen resistance associated with drug therapy or disease states in vivo may not be diagnosed by in vitro assay of cultured fibroblasts. Sperm function assays The scope of clinical testing of sperm function has until very recently been limited to the subjective assessment of sperm motility. The ability of sperm to reach the site of fertilization in the oviduct and to fertilize mature oocytes is a major precondition for achieving a pregnancy. Recent advances have developed three areas of clinical testing of sperm function. These are the more sophisticated analysis of directional sperm motility by the use of objective measures, the quantification of sperm penetration into cervical mucus and the fertilization assays based on human (homologous) or hamster (heterologous) assay systems (Blasco, 1984). The developments in the automated objective quantification of sperm motility include the development of high-speed cinemicrography or multiple exposure microphotography (Makler, 1978) and laser-light scattering (Lee et ai , 1982) methods as non-invasive measures of sperm swimming speed. These tests promise to become standard measures once commercial apparatus is available. The penetration of human sperm into midcycle cervical mucus in vivo (post-coital test) or into capillary tubes containing midcycle mucus or biological substitutes (in vitro test) also constitute useful tests of functional sperm maturity. These tests are valuable adjuncts to facilitate determination of sperm function, especially where motility is inconsistent or marginal. The in vitro test is particularly useful in that the husband's sperm is tested simultaneously against his wife's and normal mucus , whereas his wife's mucus is also cross-tested against a donor semen sample as well as the husband's sperm. This four -way cross-over testing allows control over whether the test sperm and/or mucus are normal or not. In particular, poor quality mucus that negates the validity of the post-coital test can be identified. A satisfactory result can indicate that sperm function is adequate, although poor results need to be repeated under optimal conditions of mucus and semen sampling before a negative result can be considered conclusive. The limitations of these tests are that the timing of the test is critical , since poor quality cervical mucus from mistimed specimens or specimens of mucus from anovulatory or drug-treated cycles may give misleading results. In addition, these tests are only semi-objective and semi-quantitative and cannot be replicated or compared within the same menstrual cycle. Because of these limitations these tests are most useful in assessing sperm function only after other tests have been completed, and are most useful if they can be repeated on several occasions such as during a course of treatment intended to improve sperm function .

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More recently, the fertilizing capacity of human sperm in heterologous (hamster) or homologous (human in vitro fertilization) test systems have been developed. The heterologous sperm fertilization/fusion assay was developed following the observations that, following the removal of the zona pellucida, superovulated hamster oocytes are capable of undergoing fusion and decondensation of the internalized sperm head (but not further cleavage) when exposed to sperm from human or many other species. This non-specificity of the hamster oocyte appears to be unique to this particular species. As a test system the heterologous fusion assay is useful since it can be applied widely and repeatedly on the same subject under various conditions of treatment. In addition it appears to measure an aspect of sperm function that is at least partially distinct from other measures of sperm funct ion (Aitken et aI, 1982) . For example, the application of this test has demonstrated clearly the ability of human IgO sperm antibodies to interfere with sperm-egg fusion (Haas et al, 1982). The limitations of this test are that it is a highly skilled bioassay and results are dependent on the conditions of performance of the assay (Rogers et al, 1983). The proportion of oocytes penetrated by sperm of fertile men varies from 10-100% making diagnosis in an individual case abnormal only if the penetration rate is less than 10%. The role of this assay in clinical evaluation of male fertility remains to be established. However, it appears that its most valuable role might be in serial studies on the same patient under a variety of conditions such as during treatment. The advent of human in vitro fertilization has the potential to produce valuable new information on human sperm fertilizing capacity in vitro. Within severe ethical and practical limitations on availability, these tests, as offshoots of clinical therapeutic procedures, promise to afford a standard against which other assays of human sperm fertilizing capacity can be measured. The clinical value of these fertilization assays has yet to be clearly established, and the reproducibility of the methods needs to be strengthened before they can be regarded as having diagnostic value for individual patients. In addition , correlations between the heterologous hamster assay and the homologous human system will need to be clarified.

Semen biochemistry A large variety of substances, both endogenous and exogenous, has been detected in seminal plasma which in man is largely of seminal vesicle origin (75%) with smaller contributions from the prostate (20%) and the testes and epididymes (5%). Biochemical tests can contribute to the understanding of both testicular and sex accessory gland function since certain substances in the semen are derived from particular glands and the elaboration of these materials into the semen gives some indication of the state of accessory gland function (Mann and Lutwak-Mann , 1981). Seminal vesicle function can be inferred from fructose levels in the semen. Absence of seminal fructose in a man with azoospermia is consistent with agenesis of the vas deferens and seminal vesicles. Low levels of seminal fructose are indicative of deficient androgen supply or abnormal function of the seminal vesicles. Similar interpretations can be made about lowered seminal fluid content of citrate and acid phosphatase which indicate deficient prostatic

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exocrine function due either to hypoandrogenism or to prostatitis. Other compounds found in seminal plasma, such as glycerophosphorylcholine, carnitine or sialoproteins, may represent valuable markers of epididymal function since seminal fluid levels are lowered in hypogonadism or vasectomized men. A similar role for transferrin as a Sertoli cell marker, has been suggested (Holmes et al, 1982). An ideal seminal plasma marker, secreted into the seminal plasma exclusively by either the testis or the epididymis, with levels that are easily detectable in normals but absent in vasectomized men, is still sought. Such a marker would be valuable in the detection of partial or unilateral obstruction of the epididymis or efferent ducts as well as serving as an index of Sertoli cell function. Testicular biopsy The use of testicular biopsies to investigate testicular function has continued to decline in recent years. The reasons for this include the limited ability to determine testicular function or the aetiology of testicular damage from the relatively stereotypic histological appearances as well as the greater sensitivity and diagnostic power of basal and stimulated hormone assays. Although the range of testicular biopsy appearances among infertile men have been well-characterized, there is little information of a prognostic or aetiological nature that is provided by this procedure. Spermatogenesis can be measured in a quantitative manner more accurately by the less invasive procedures of semen analysis and the FSH assay. Furthermore, Leydig cell function is determined most accurately by hormone radioimmunoassay of basal LH and testosterone levels before and after HCG stimulation. The only remaining definite indication for testicular biopsy is to confirm normal spermatogenesis in men suspected of having sperm outflow obstruction after preliminary investigations that demonstrate normal testicular size, normal basal FSH and LH levels and persistent azoospermia. Since the major indication for testicular biopsy is now the investigation of ductular obstruction, all biopsy procedures should be accompanied by visualization and exploration of the epididymis and scrotal vas deferens for signs of scarring or intraluminal obstruction by inspissated secretions (Hendry et ai, 1983). Apart from vasectomy, the majority of cases of obstructive azoospermia involve the epididymis, so that organ should be examined particularly carefully since the external appearance can help in making an aetiologic diagnosis of obstruction as due to extrinsic (scarring and/or infection) or intrinsic (Young's syndrome) causes. In very few instances a testicular biopsy may be indicated in oligospermic men to give prognostic information to couples considering such measures as artificial insemination with donor semen where a very poor histological appearance may suggest that, in the short term, alternative therapies should be considered. Cytogenetic studies The wide availability of modern cytogenetic methods-including leucocyte karyotyping with specialized banding techniques for differential staining of chromosome segments-have largely supplanted the buccal smear (Skak-

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kebaek, 1981). Major chromosomal disorders due to non-disjunction or translocations are found in about 1:500 live-born males. The most consistent chromosomal disorder associated with testicular dysfunction is Klinefelter's syndrome (47 XXY) which is associated with severe hypogonadism and complete spermatogenic failure (Hsueh et aI, 1978). The classical phenotype of tall , eunuchoidal individuals with gynaecomastia and small, firm testes «4 rnl) is not always present but the hypoplastic testes are quite characteristic. The cytogenetic diagnosis of Klinefelter's syndrome usually implies a prognosis of irreversible testicular failure. Androgen replacement is indicated in such men, and if fertility is desired , the only options are artificial insemination of the spouse with donor semen or adoption. In giving a prognosis, it should be remembered that Klinefelter's mosaics with partial preservation of testicular function and genotypic proof of paternity have been described but are exceptional. The relationship of other chromosomal disorders, including additions of further X or Y chromosomes or trisomies of autosomal chromosomes, to testicular dysfunction remain obscure since the apparent associations of a chromosomal disorder with testicular dysfunction may be artificially produced by ascertainment bias when surveys are based on institutional data (Berkson's bias). The rare 46 XX male appears to be a variant of Klinefelter's syndrome since the HY antigen is expressed, indicating the presence of an active , translocated Y chromosome. Evidence for the association of balanced reciprocal translocations of autosomal or sex chromosomes with testicular failure is more consistent and may be due to interference with the efficiency of meiosis. Minor chromosomal disorders including a variety of markers and chromosome polymorphisms may occur with increasing frequency among infertile men but are of uncertain pathological consequence in view of the lack of evidence from prospective samplings of the normal male population showing a correlation of these chromosomal markers with testicular pathology. Cytogenetic investigations are warranted in men with evidence of unexplained primary hypogonadism (including pubertal delay) and/or severe spermatogenetic damage. The diagnostic yield is greatest when screening is limited to men with small testes and/or azoospermia with elevated FSH levels. Consequently cytogenetic studies should be performed after baseline investigations in selected men.

Immunological tests Sperm antibodies have been associated with infertility in both men and women. Autoimmunization of men to sperm antigens is most common in men after vasectomy, when between 60 and 80% of men develop and maintain high titres of circulating sperm antibodies for years. The presence of sperm antibodies does correlate with a lower likelihood of impregnation after reversal of vasectomy. The relatively high frequency with which congenital or acquired vas obstruction is associated with high titres of sperm antibodies is useful in the diagnosis of inadvertent obstruction of the vas. Spontaneous sperm autoimmunity is detected in about 6% of infertile

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but not in normal men (Handelsman et aI, 1983). The presence of high titres of sperm antibodies is also associated with evidence of testicular damage and sperm dysfunction. It is not certain whether the immunological reactions are part of a primary form of autoimmune orchitis or whether they follow other forms of testicular damage, amplifying the deleterious effects of the precipitating causes. However, it is clear that such sperm antibodies are associated with severe infertility and that the antibodies can interfere directly with sperm function. Pregnancies to the partners of men with sperm antibodies have been reported in a variety of uncontrolled trials of either sperm washing techniques to remove the bound antibody or pharmacological therapy to reduce sperm antibody production. Methods for detecting sperm antibodies have been the traditional immunological agglutinating and immobilizing assays (Rose et al, 1976). These procedures have been standardized, and when performed by experienced personnel are reproducible between laboratories. The sperm agglutinating antibody assay is sensitive but only specific for sperm antibodies above a titre of 1/32, whereas the sperm immobilizing assay is insensitive but highly specific with any detectable titre being abnormal. Seminal fluid sperm antibody tit res are usually lower than in blood plasma proportionate to total protein levels in the two fluids. The inherent limitations of the classical immunological tests have stimulated a search for more sensitive and precise assays for sperm antibodies. A variety of new radioassays based on the ability of radiolabelled antibodies to detect the binding of antibodies from blood or other secretions to intact sperm or extracts of sperm appear to have promise for the more widespread application of sperm antibody testing (Haas et al, 1980). The application of sperm antibody testing is largely restricted to investigation of men with infertility. However, the best guidelines for testing remain debatable. In larger referral institutions, all patients are screened with sperm agglutinating antibody assays. However, the yield is relatively low. Reliable guidelines are difficult to specify since the scope of sperm antibody interference with sperm fertilizing capacity remains uncertain. High titres of sperm antibodies are usually, but not always, associated with sperm that demonstrate a characteristic vigorous 'shaking' , non-progressive motility. In other cases the presence of sperm antibodies may only be associated with low sperm motility. Since sperm antibodies are rarely detected in men with normal semen analysis, testing for immunological infertility should be restricted to infertile men with reduced sperm penetration of cervical mucus or abnormal semen analysis, particularly low motility. The extension of sperm antibody assays to seminal plasma has yet to be proven to have more diagnostic value than testing of serum, and the levels in these two media are usually highly correlated but higher in serum, making for easier detection. The most efficient testing procedure is to screen with a microtitre plate sperm agglutinating assay, accepting only values above a titre of 1/32 as significant positives. All positive results should be confirmed with a repeat assay on a second serum sample, where possible, and a sperm immobilizing antibodies assay to confirm the specificity of the finding.

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Antibodies to hormones or their receptors have been increasingly recognized in recent years as potential causes of endocrine dysfunction. Antibodies to heG (Sokol et al, 1981), LH (Healey et al, 1978), FSH (Rabinowitz et al, 1979) and GnRH (Lindner et al, 1981) associated with acquired hormone resistance induced by therapeutic injections have been described. At present, the occurrence of spontaneous autoantibodies to gonadal hormones or receptor antibodies without previous exposure to exogenous hormones have not been reported. Immunological testing is also valuable in genotypic confirmation of paternity (Lee and Williams, 1982) since extramarital paternity is relatively common (Schacht and Gershowitz, 1963) and seriously confounds analytical studies of infertility. This procedure uses patterns of highly polymorphic inherited genetic markers such as a panel of blood group markers or tissue typing histocompatibility (HLA) antigens to determine the likelihood of paternity by the putatitve father. The principle of this test is the assignment of the child's antigens to those of maternal and paternal origin by direct comparison of the mother's and child's antigen patterns. Any inconsistency between the child's and putative father's genotype in well-defined marker systems can exclude paternity, and if tire paternal contribution to the child's genotype is consistent with the father's genotype, the exact probability of this coincidence by chance can be calculated, assuming that the prevalence of the genotypes is known within the community. The major limitation of this procedure is the cost and the unacceptability of large sample volumes of blood required to be drawn from children. This sort of procedure should be restricted to research protocols and only undertaken after fully informed consent of the couple to the potential implications of various results that might be obtained. Radiological investigations Radiological investigations of the vascular and ductal system of the male genital tract have been expanded considerably. A variety of scanning procedures have been described to facilitate the diagnosis of varicoceles. These include isotope procedures to visualize scrotal blood pooling by radionuclide scanning (Freund et al, 1980), venography to demonstrate retrograde venous flow down the internal spermatic vein, thermography to demonstrate asymmetrical increases in lateral scrotal temperature, and Doppler ultrasound as a non-invasive measure of retrograde flow patterns (Hirsh et al, 1980). Such scanning procedures are most useful in delineating varicocele in men in whom scrotal examination is inconclusive or difficult due to scrotal shape or obesity, and in the detection of subclinical varicocele. The clinical value of such tests has yet to be proven, and considering the increasingly controversial status of varicocele itself it is unlikely to be resolved in the near future. The use of vasography in the diagnosis or surgery of obstructive azoospermia has largely ceased since it has been increasingly recognized that the procedure of cannulating the delicate vas deferens is more likely to cause obstruction than to diagnose it. The vast majority of clinically

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detected obstructive lesions are in the epididymis which is only poorly visualized and easily traumatized by vasography. Consequently, vasography has very limited diagnostic potential and considerable risk of requiring excision and vasovasostomy at the puncture site. One of the very few indications for vasography remains the unusual instance of suspected vas obstruction high in the inguinal canal (most often postsurgical adhesions following childhood inguinal herniorraphy) when injection of radio-opaque dye into the scrotal vas deferens with injection towards the prostatic end may demonstrate the site of vasal obstruction. Angiography of the pelvic vasculature has been increasingly applied to diagnose impotence due to penile vascular insufficiency associated with vascular 'steal' syndromes. The frequency of these syndromes as a cause of impotence has not been clarified and the efficacy of surgery for such partial perfusion defects remains uncertain. This procedure can be carried out by competent vascular radiographers; however, it is only indicated following clinical and laboratory investigations that indicate the likelihood of significant organic impotence for which vascular or prosthesis surgery would be considered.

Nocturnal penile tumescence (NPT) monitoring This procedure has revolutionized the diagnostic armamentarium for impotence. In this test, impotent men are attached to circumferential strain gauges encircling the base, mid-shaft and tip of the penis while they sleep in a fully equipped sleep laboratory. Concurrent monitoring of electrooculograms and electroencephalograms allow determination of sleep depth stages. In men with pure psychogenic impotence, erections occur during most periods of rapid eye movement (REM) sleep , and the frequency and duration of erectile periods are comparable with men of normal potency. In men with erectile impotence of organic origin, erectile frequency and duration are greatly reduced or absent. Since adequate periods of normal REM sleep are required for interpretation of the records from the penile strain gauges, in some cases recordings of a second night in the sleep laboratory may be required . Abnormally flat NPT recordings cannot distinguish between vascular and neurological causes of organic impotence, and some types of organic impotence- such as that associated with androgen deficiency-may have normal results in NPT tests. Conversely, severe depression may be associated with abnormal NPT traces. Finally, the results of NPT monitoring, although an extremely valuable adjunct to diagnosis of impotence, cannot be regarded in isolation, especially since these tests cannot measure the degree of penile turgescence or rigidity nor the patients' satisfaction with the sexual function that they have. Simplifications ofthe NPT methodology are under development but still require more extensive clinical evaluation for sensitivity and specificity . REFERENCES Ad ashi EY (1984) Clomiphene citr ate : mechanism(s) and site( s) of action-a hypothesis revisited . Fertility and Sterility 42: 331-344 .

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Aiman J , Griffin JE, Gazak JM , Wilson JD & MacDonald PG (1979) Androgen insensitivity as a cause of infertility in otherwise normal men. New England Journal of Medicine 300: 223-227. Aitken RJ , Best FSM, Richardson DW et al (1982) An analysis of sperm function in cases of unexplained infertility: conventional criteria, movement characteristics, and fertilizing capacity. Fertility and Sterility 38: 212-221. Ash P (1980) The influence of radiation on fertility in man. British Journal of Radiology 53: 271-278 . Baker HWG & Hudson B (1974) Male gonadal dysfunction . Clini cs in Endocrinology and Metabolism 3: 507-531. Baker HWG, Burger HG , De Kretser DM et al (1976) Testicul ar control of follicle stimulating hormone. Recent Progress in Hormone Research 32: 429-476 . Belsey MA , Eliasson R , Gallegos AJ et al (1980) Laboratory Manual for the Examination of Human Semen and Semen-cervical Mucus Interaction . Singapore: Press Concern. Birnie GG, McLeod TIF & Watkinson G (1981) Incidence of sulphasalazine-induced male infertility. Gut 22: 452-455. Blasco L (1984) Clinical tests of sperm fertilizing ability. Fertility and Sterility 41: 177-192. Boyden TW & Pamenter RW (1983) Effects of ethanol on the male hypothalamic-pituitarygonadal axis. Endocrine Reviews 4: 389-395. Burger HG & De Kretser DM (1981) The Testis. New York: Raven Press. Carlson HE, Ippoliti AF & Swerdloff RS (1981) Endocrine effects of acute and chronic cimetidine administration. Digestive Diseases and Sciences 26: 428-432. Catt KJ , Harwood JP, Clayton RC et al (1980) Regulation of peptide hormone receptors and gonadal steroidogenesis. Recent Progress in Hormone Research 36: 557-622 . Davidson JM , Kwan M, Greenleaf WJ (1982) Hormonal replacement and sexuality in men. Clinics in Endocrinology and Metabolism 11: 599-624 . Fowler JE (1981) Infections of the male reproductive tract and infertility: a selected review . Journal of Andrology 3: 121-131. Franchimont P, Verstraelen-Proyard J , Hazee-Hagelstein MT et al (1979) Inhibin: from concept to reality. Vitamins and Hormones 37: 244-302. Freund J , Handelsman DJ , Bautovich GJ , Conway AJ & Morris J (1980) Varicocele detection by radio-nuclide blood pool scanning. Radiology 137: 227-230. Glass AR, Swerdloff RS, Bray GA, Dahms WT & Atkinson RL (1977) Low serum testosterone and sex-hormone-binding globulin in massively obese men. Journal ofClinical Endocrinology and Metabolism 45: 1211-1219 . Griffin JE & Wilson JD (1980) The syndromes of androgen resistance . New England Journal of Medicine 302: 198-209. H aas GG , Cines DB & Schreiber AD (1980) Immunological infertility: identification of patients with sperm antibodies . New England Journal of Medicine 303: 722-727. Haas GG , Sokoloski JE & Wolf DP (1980) The interfering effect of human IgG antisperm antibodies on human sperm penetration of zona-free hamster eggs . American Journal of Reproductive Immunology 1: 40-43. Hahn EW, Feingold SM , Simpson L & Batata M (1982) Recovery from aspe rmia induced by low dose radiation in seminoma patients. Cancer 50: 337-340 . .Landelsman OJ & Turtle JR (1983) Testicular damage after radioactive iodine therapy for thyroid cancer. Clinical Endocrinology 18: 465-472. Handelsman OJ, Conway AJ, Radonic I & Turtle JR (1983) Prevalence , testicular function and seminal parameters in men with sperm antibodies. Clini cal Reproduction and Fertility 2: 39-45. H andelsman DJ, Conway AJ, Boylan LM & Turtle JR (1984a) Youngs syndro me : obstructive azoospermia and chronic sinopulmonary infections. New England Journal of Medicine 310: 3-9. Hand elsman DJ, Conway AJ , Boylan LM & Turtle JR (1984b ) Testicular function in potential spe rm donors: normal rang es and the effects of smo king and varicocele. International Journal of Andrology 7: 369-382. Harman SM, Tsitsouras PD , Cost a PT , Leriaux OL & Sherins RJ (1982) Evaluation of pituitary gonadotropic funct ion in men : value of luteinizing hormone-releasing hormone response versus basal luteinizing hormone level for discrimination of diagnosis. Journal of Clinical Endocrinology and Metab olism 54: 196-200.

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Healy DL, Fraser IS, Lee VWK, Shearman RF & Burger HG (1978) Characteristics of an antiluteinizing hormone isoantibody produced during gonadotropin induction of ovulation. Journal of Clinical Endocrinology and Metabolism 47: 823-827. Hendry WF, Parslow JM & Stedronska J (1983) Exploratory scrototomy in 168 azoospermic males. British Journal of Urology 55: 785-791. Hirsh A V, Ketlett MJ, Robertson G & Pryor JP (1980) Doppler flow studies, venography and thermography in the evaluation of varicoceles of fertile and infertile men. British Journal of Urology 52: 560-565. Holmes SD, Lipshultz LI & Smith, PG (1982) Transferrin and gonadal function in man. Fertility and Sterility 38: 600-604. Hsueh WA, Hsu TH & Federman DD (1978) Endocrine features of Klinefelter's syndrome. Medicine 57: 447-461. James WH (1980) Secular trends in reported sperm counts. Andrology 12: 381-383. Kalra SP & Kalra PS (1983) Neural regulation of luteinizing hormone secretion in the rat. Endocrine Reviews 4: 311-351. Karpas AE, Matsumoto AE, Paulsen CA & Bremner WJ (1983) Elevated serum follicle stimulating hormone levels in men with normal seminal fluid analyses. Fertility and Sterility 39: 333-336. Knobil E (1980) The neuroendocrine control of the menstrual cycle. Recent Progress in Hormone Research 36: 53-88. Lambert B (1951) The frequency of mumps and of mumps orchitis. Acta Genetica et Statistica Medica (Supplement 1) 2: 1-196. Lee CL & Williams G (1982) How to deal with an indirect exclusion of paternity. American Journal of Clinical Pathology 77: 204-206. Lee WI, Gaddum-Rosse P, Smith WD, Stenohever M & Blandau RJ (1982) Laser light-scattering study of the effect of washing on sperm motility. Fertility and Sterility 38: 62-67. Lieblich JM, Rogol AD, White BJ & Rosen SW (1982) Syndrome of anosmia with hypogonadotropic hypogonadism (Kallman syndrome). American Journal of Medicine 73: 506-517. Lindner J, McNeil LW, Marney S et al (1981) Characterization of human anti-luteinizing hormone-releasing hormone (LRH) antibodies in the serum of a patient with isolated gonadotropin deficiency treated with synthetic LRH. Journal of Clinical Endocrinology and Metabolism 52: 267-270. Lipshultz Ll & Howards SS (1983) Infertility in the Male. New York: Churchill Livingstone. MacLeod J & Wang Y (1979) Male fertility potential in terms of semen quality: a review of the past, a study of the present. Fertility and Sterility 31: 103-112. Makler A (1978) A new multiple exposure photography method for objective sperm motility determination. Fertility and Sterility 30: 192-199. Mann T & Lutwak-Mann C (1981) Male Reproductive Function and Semen. Berlin: Springer-Verlag. Muta K, Kato KI, Akamura Y & Ibayashi H (1981) Age-related changes in the feedback regulation of gonadotropin secretion by sex steroids in men. Acta Endocrinologica 96: 154-162. Odell WD & Swerdloff RS (1978) Abnormalities of gonadal function. Clinical Endocrinology 8: 149-180. Padron RS, Wischusen J, Hudson B, Burger HG & De Kretser DM (1980) Prolonged biphasic response of plasma testosterone to single intramuscular injections of human chorionic gonadotropin. Journal of Clinical Endocrinology and Metabolism 50: 11001104. Palacios A, Campfield LA, McClure RD, Steiner B & Swerdloff RS (1983) Effect of testosterone enanthate on hematopoiesis in normal men. Fertility and Sterility 40: 100-104. Perryman RL & Thorner MO (1981) The effects of hyperprolactinemia on sexual and reproductive function in men. Journal of Andrology 5: 233-242. Rabinowitz D, Benveniste R, Lindner J, Lorber D & Daniell J (1979) Isolated folliclestimulating hormone deficiency revisited. New England Journal of Medicine 300: 126-128. Reiter RJ (1980) The pineal and its hormones in the control of reproduction of mammals. Endocrine Reviews 1: 109-131.

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Rogers BI, Perrault SD, Bentwood BJ et al (1983) Variability in the human-hamster in vitro assay for fertility evaluation . Fertility and Sterility 39: 204-211 . Rose NR. Hjort I, Rumke P, Harper MIK & Vyozev 0 (1976) Techniques for detection of iso- and auto-antibodies to human spermatozoa. Clinical and Experimental Immunology 23: 175-195. Schacht, LE & Gershowitz H (1963) Frequency of extra-marital children as determined by blood groups. In Proceedings of the Second International Congress of Human Genetics, Rome. Italy. 1961, volume 2: 894-897. Schilsky RL. Lewis BJ, Sherins, RJ & Young RC (1980) Gonadal dysfunction in patients receiving chemotherapy for cancer. Annals of Internal Medicine 93: 109-114. Shaarawy M & Mahmoud KZ (1982) Endocrine profile and semen characteristics in male smokers. Fertility and Sterility 38: 255-257 . Skakkebaek NE (1981) Cytogenetics in male hypogonadism . In Burger HG & De Kretser OM (eds) The Testis , pp 401-417 . New York: Raven Press. Snyder, PJ & Lawrence DA (1980) Treatment of male hypogonadism with testosterone enenthate . Journal of Clinical Endocrinology and Metabolism 51: 1335-1339. Snyder PI, Rudenstein RS, Garder OF & Rothman JG (1979) Repetitive infusion of gonadotropin-releasing hormone distinguishes hypothalamic from pituitary hypogonadism. Journal of Clinical Endocrinology and Metabolism 48: 864-868. Sokol RZ, McClure RD, Peterson M & Swerdloff RS (1981) Gonadotropin therapy failure secondary to human chorionic gonadotropin-induced antibodies. Journal of Clinical Endocrinology and Metabolism 52: 929-933. Sokol RZ, Palacios A, Campfield LA, Saul C & Swerdloff RS (1982) Comparison of the kinetics of injectable testosterone in eugonadal and hypogonadal men. Fertility and Sterility 37: 425-430. Spark RF, White RA & Connolly PB (1980) Impotence is not always psychogenic: newer insights into hypothalamic-pituitary-gonadal dysfunction. J.A .M.A . 243: 750-755. Styne , OM & Grumbach MM (1978) Puberty in the male and female : its physiology and disorders. In Yen SSC & Jaffe RB (eds) Reproductive Endocrinology, pp 189-240. Philadelphia: WB Saunders. Sutherland RL, Murphy LC, Foo MS et al (1980) High-affinity anti-oestrogen binding site distinct from the oestrogen receptor. Nature 288: 273-275. Swerdloff RS & Boyers SP (1982) Evaluation of the male partner of an infertile couple. An algorithmic approach . J.A .M.A. 247: 2418-2422. Wagner G & Green R (1981) Impotence: Physiological, Psychological, Surgical Diagnosis and Treatment. New York: Plenum Press. Waxman IHX, Terry YA, Wrigley PFM et al (1982) Gonadal function in Hodgkins disease: long-term follow-up of chemotherapy. British Medical Journal 285: 1612-1613_ Wheeler MJ , Crisp AH, Hsu LKG & Chen CN (1983) Reproductive hormone changes during weight gain in male anorectics. Clinical Endocrinology 18: 423-429 . Whitehead ED & Leiter E (1981) Genital abnormalities and abnormal semen analyses in male patients exposed to diethylstilbestrol in utero. Journal of Urology 125: 47-50. Whitehead E , Shalet SM, Blackledge G ct al (1982) The effect of Hodgkins disease and combination chemotherapy on gonadal function in the adult male . Cancer 49: 418-422. Wilson ID & Griffin IE (1980) The use and misuse of androgens. Metabolism 29: 1278-1295.