- Email: [email protected]
Effect of growth hormone treatment on testicular function, puberty, and adrenarche in boys with non-growth hormone–deficient short stature: A randomized, double-blind, placebo-controlled trial
Effect of growth hormone treatment on testicular function, puberty, and adrenarche in boys with non-growth hormone–deficient short stature: A randomized, double-blind, placebo-controlled trial Ellen Werber Leschek, MD, James F. Troendle, PhD, Jack A. Yanovski, MD, PhD, Susan R. Rose, MD, Donna B. Bernstein, RN, Gordon B. Cutler, Jr, MD, and Jeffrey Baron, MD
Objective: To evaluate the effect of growth hormone (GH) therapy on pubertal onset, pubertal pace, adult testicular function, and adrenarche in boys with non-GH-deficient short stature. Study design: Randomized, double-blind, placebo-controlled trial. GH (0.074 mg/kg, subcutaneously, 3 times per week) or placebo treatment was initiated in prepubertal or early pubertal boys and continued until near final height was reached (n = 49). Statistical significance was assessed by survival analysis, repeated-measures analysis of variance, and Student t test. Results: GH therapy did not affect the age at pubertal onset, defined either by testicular volume >4 mL or by testosterone concentration >1.0 nmol/L (30 ng/dL). GH treatment also did not affect the pace of puberty, defined either by the rate of change in testicular volume or testosterone concentration during the 4 years after pubertal onset. In boys followed up to age ≥16 years during the study, there were no significant differences in final testicular volume or in plasma testosterone, luteinizing hormone, or follicle-stimulating hormone concentrations. The pace of adrenarche, assessed by change in dehydroepiandrosterone sulfate levels over time, also did not differ significantly between the GH and placebo groups. Conclusion: Our findings suggest that GH treatment does not cause testicular damage, alter the onset or pace of puberty, or alter the pace of adrenarche in boys with non-GH-deficient short stature. (J Pediatr 2001;138:406-10)
From Developmental Endocrinology Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland; Biometry and Mathematical Statistics Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland; Department of Pediatrics, University of Tennessee Health Sciences Center, Memphis; and Eli Lilly and Company, Indianapolis, Indiana.
Drs Yanovski and Baron are Commissioned Officers in the United States Public Health Service. Supported in part by Eli Lilly and Co. Submitted for publication Mar 17, 2000; revision received June 30, 2000; accepted Aug 30, 2000. Reprint requests: Ellen Leschek, MD, DEB/NICHD, National Institutes of Health, Building 10, Room 10N262, 10 Center Dr, MSC 1862, Bethesda, MD 20892-1862. 9/21/111332 doi:10.1067/mpd.2001.111332
406
Growth hormone is often used to treat children with non-GH-deficient short stature1 despite the absence of any definitive, long-term, well-controlled studies of efficacy. Long-term studies lacking concurrent controls have yielded conflicting results as to whether GH therapy increases the final height of children without GH deficiency. Some of these studies suggest that GH may accelerate puberty, thus causing earlier epiphyseal fusion and offsetting the positive effects of GH.2-4 GH administration may also accelerate puberty in children with GH deficiency and nonhuman primates.5-10 DHEA-S FSH GH LH TV
Dehydroepiandrosterone sulfate Follicle-stimulating hormone Growth hormone Luteinizing hormone Testicular volume
In contrast, a recent case-report series suggests that GH may cause testicular damage in boys with non-GH-deficient short stature. Bertelloni et al11 described 4 men (aged 17-25 years) with hypergonadotropic hypogonadism who had previously received GH as children. Evidence suggesting hypogonadism included low testicular volume (4 of 4 patients, mean = 11 mL), low serum testosterone concentration (1 patient), elevated basal follicle-stimulating hormone levels (4 patients), elevated basal luteinizing hormone levels (3 patients), and de-
LESCHEK ET AL
THE JOURNAL OF PEDIATRICS VOLUME 138, NUMBER 3 Table I. Clinical characteristics of the subjects at initiation of treatment*
Pubertal onset
Pubertal pace
Testicular function
All subjects
Analysis
Placebo
GH
Placebo
GH
Placebo
GH
Placebo
GH
No. of subjects Chronological age (y) Bone age (y) TV (mL)
12 11.5 ± 0.4 10.2 ± 0.5 3.4 ± 1.0
11 12.0 ± 0.5 10.1 ± 0.5 3.1 ± 0.5
13 12.2 ± 0.4 10.7 ± 0.4 3.7 ± 0.4
15 12.7 ± 0.4 10.7 ± 0.5 3.6 ± 0.3
13 13.3 ± 0.3 11.7 ± 0.3 7.0 ± 1.2
19 13.2 ± 0.4 11.2 ± 0.4 5.5 ± 0.7
24 12.3 ± 0.3 10.9 ± 0.3 4.9 ± 0.8
25 12.8 ± 0.3 10.9 ± 0.4 4.9 ± 0.6
Values are expressed as mean ± SEM. GH, Growth hormone; TV, testicular volume. *Different subsets of subjects were used for different analyses (age at pubertal onset, pubertal pace, testicular function at completion of treatment).
creased sperm concentration and motility (4 patients). These possible effects of GH therapy on the timing of puberty and on testicular function have been proposed based on case-report series and on clinical trials lacking concurrent, randomized control groups. To evaluate these issues more rigorously, we evaluated the effects of GH administration on: (1) the age at pubertal onset, (2) the pace of pubertal progression, (3) testicular function after completion of puberty, and (4) the pace of adrenarche in males without GH deficiency enrolled in a randomized, double-blind, placebocontrolled trial of GH therapy.
METHODS Subjects Subjects were participating in a randomized, double-blind, placebo-controlled trial of GH for non-GH-deficient short stature, which has been ongoing since 1987. Inclusion criteria at entry were (1) age 10 to 16 years, (2) bone age ≤13 years, (3) testicular volume ≤10 mL, (4) proportionate short stature with absolute and/or predicted height ≤–2.5 SD for age, and (5) peak stimulated GH ≥7 ng/mL. Subjects were excluded if they had a chronic illness or a known genetic syndrome or were receiving any medications likely to affect growth. The current analysis was restricted to male subjects. Table I shows the clinical characteristics of the subjects at initiation of treatment.
Table II. Age (mean ± SEM) at pubertal onset defined by TV >4 mL or by testosterone concentration >1.0 nmol/L (30 ng/dL)
Age at pubertal onset (y) Criterion
Placebo
GH
TV >4 mL Testosterone >1.0 nmol/L
13.5 ± 0.5 13.5 ± 0.6
13.3 ± 0.5 14.1 ± 0.4
GH, Growth hormone; TV, testicular volume.
Protocol The protocol was approved by the Institutional Review Board of the National Institute of Child Health and Human Development. Informed consent was obtained from a parent, and assent was given by each child. Subjects were evaluated every 6 months, starting 6 months before the initiation of treatment. At each visit, LH, FSH, testosterone, and dehydroepiandrosterone sulfate concentrations were measured 3 times at 20-minute intervals. TV was measured with a Prader orchidometer,12 and bone age was determined by the method of Greulich and Pyle.13 Treatment with either GH (Humatrope [Eli Lilly and Company, Indianapolis, Ind], 0.074 mg/kg injected subcutaneously 3 times per week) or placebo was started 6 months after enrollment and continued until near final height was reached. This dose and frequency were selected because they represent regimens commonly used at the time of study design. To avoid compromising this ongoing, double-blind study examining the effect of GH on
adult height, no variables involving growth were examined. Individual data were available only to a collaborating statistician (J.F.T.).
Hormone Assays LH, FSH, testosterone, and DHEAS concentrations were measured by radioimmunoassay (Covance Laboratories, Vienna, Va).14-17
Statistical Analysis Results were expressed as mean ± SEM. For the analysis of pubertal onset, subjects were included if they were prepubertal (TV ≤4 mL or testosterone concentration ≤1.0 nmol/L [30 ng/dL], depending on the analysis) at the initiation of treatment. Survival analysis was used to examine these data. Tests of equality of survival curves were performed by the log-rank test provided by Proc Lifetest in the SAS statistical software package (SAS Institute Inc, Cary, NC). For the analysis of pubertal pace, subjects were included if they were prepubertal at the initial evaluation and started pu407
LESCHEK ET AL
A
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B
Fig 1. Pace of puberty as defined by testicular volume (A, n = 29) or by plasma testosterone concentration (B, n = 28) in subjects receiving GH (solid circles, solid lines) or placebo (open circles, dashed lines). Symbols and error bars represent mean ± SEM.
and treatment on DHEA-S values were assessed by repeated-measures analysis of variance, including a term for initial bone age deficit.
RESULTS Age at Pubertal Onset
Fig 2. Pace of adrenarche as defined by mean ± SEM plasma DHEA-S concentration in subjects (n = 35) receiving GH (solid circles, solid line) or placebo (open circles, dashed line).
In the boys who were prepubertal at the start of the study, GH did not affect the age at onset of puberty, defined either by TV >4 mL or by testosterone concentration >1.0 nmol/L (30 ng/dL) (Table II). The duration of treatment before pubertal onset was 1.6 ± 0.2 years versus 2.3 ± 0.3 years (GH vs placebo).
Pace of Pubertal Progression berty (TV >4 mL) during the study. Data from the first 4 years after onset of puberty were included. Pubertal pace was assessed by repeated-measures analysis of variance with the use of the Proc Mixed program in the SAS software package. Correlation between observations on the same patient was assumed to decline with increase in time difference between the observations. The models included terms for age at onset of puberty and initial bone age deficit (bone age minus 408
chronological age). For the analysis of testicular function after completion of puberty, subjects were included if they were ≥16 years of age at the time of analysis. The final measurements obtained for each subject were analyzed by Student t test to compare the GH and placebo groups. If a statistically significant difference in variance was found by F test, the approximate t test with the df of Satterthwaite was used. For the analysis of adrenarche, all subjects were included. The effects of age
We analyzed the rate of pubertal progression during the 4 years after the onset of puberty (defined by TV >4 mL). GH treatment did not affect the rate of increase of TV (4.1 ± 0.3 vs 4.1 ± 0.3 mL/y, GH vs placebo, n = 29, P = NS, Fig 1, A) or the rate of increase in testosterone (5.44 ± 0.83 vs 5.41 ± 0.87 nmol/L/y [157 ± 24 vs 156 ± 25 ng/dL/y], n = 28, P = NS, Fig 1, B). TV ≥15 mL was achieved at 15.5 ± 0.4 years of age in the GH-treated group and 15.3 ± 0.4 years of age in the placebo-treated group.
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THE JOURNAL OF PEDIATRICS VOLUME 138, NUMBER 3
Table III. Testicular volume and function (mean ± SEM) at completion of treatment and at least 1 year after completion of treatment
Completion of treatment
Age (y) Duration of treatment (y) TV (mL) Testosterone (nmol/L) (ng/dL) LH (IU/L) FSH (IU/L)
One year after completion of treatment
Placebo
GH
Placebo
GH
17.5 ± 0.2 4.2 ± 0.3 20.9 ± 0.8 20.4 ± 1.4 587 ± 41 10.7 ± 0.7 9.2 ± 1.0
17.8 ± 0.3 4.6 ± 0.3 20.7 ± 0.8 20.9 ± 1.6 603 ± 47 11.8 ± 1.2 8.9 ± 1.4
18.9 ± 0.4
19.4 ± 0.4
22.5 ± 1.6 28.8 ± 3.5 832 ± 101 11.3 ± 1.1 8.8 ± 1.0
20.9 ± 1.3 20.5 ± 1.0 592 ± 29 13.9 ± 2.6 11.1 ± 2.8
None of the differences between treatment groups were statistically significant. GH, Growth hormone; TV, testicular volume; LH, luteinizing hormone; FSH, follicle-stimulating hormone.
Testicular Volume and Function After Completion of Puberty In boys who were followed up to age ≥16 years during the study (n = 32), there were no significant differences between treatment groups in final TV or testosterone, LH, or FSH levels. Fifteen of the subjects included in this analysis were evaluated at least 1 year after discontinuation of therapy, and at that time, there were still no significant differences between treatment groups in TV or testosterone, LH, or FSH levels (Table III).
Pace of Adrenarche Adrenarche was evaluated in all boys who were followed up in the study. GH treatment did not affect the pace of adrenarche (n = 35), defined by the rate of change in DHEA-S concentration (0.69 ± 0.13 vs 0.76 ± 0.14 µmol/L/y [25.5 ± 4.7 vs 28.0 ± 5.3 µg/dL/y], GH vs placebo, P = NS, Fig 2).
DISCUSSION In boys with non-GH-deficient short stature, GH treatment did not significantly alter the age at pubertal onset, defined either by TV or by serum testosterone concentration. GH therapy also did not alter the pace of puberty, defined either by the rate of testicular growth or the rate of increase in serum testosterone.
Previous studies of children without GH deficiency treated with GH have yielded conflicting results. In some studies, the onset and pace of puberty were reportedly unaffected by GH administration.18,19 Other reports suggest that GH therapy may hasten the onset of puberty3 and/or accelerate the pace of puberty2-4 in boys with nonGH-deficient short stature. Kawai et al3 reported that GH treatment (at doses ~80% of that used in the current study) accelerates both the onset and pace of puberty in males with nonGH-deficient short stature. In contrast to these studies, our study had a doubleblind, placebo-controlled, randomized design. The only previous randomized trial to address this issue differed from our study in that the subjects were girls, the control group was untreated, and the number of subjects studied was smaller. In that study, McCaughey et al18 found that GH did not affect pubertal onset or pace. At completion of puberty and at least 1 year after the completion of treatment, there were no significant differences between the GH and placebo groups in terms of TV or plasma testosterone, LH, or FSH concentrations. Thus GH treatment did not appear to cause testicular injury. Recently, Bertelloni et al11 described 4 males without GH deficiency (ranging in age from 17 to 25 years) who developed hypergonadotropic hypogonadism
after receiving GH therapy as children (duration of treatment ranged from 4.3 to 12.4 years). The GH dose received by these patients (0.6-1.0 IU/kg/wk) was comparable to that used in the current study, but the frequency of administration (6 times per week) was greater. The median age at which these 4 patients were evaluated (18.8 years) was similar to that in the current study. Our findings suggest that the testicular dysfunction in these patients may not have been caused by GH but rather may have been caused by an underlying disorder that resulted in both short stature and hypergonadotropic hypogonadism. However, our data cannot exclude the possibility that testicular injury could be a rare, idiosyncratic reaction to GH treatment. To preserve the integrity of the double-blind trial design, we analyzed only grouped data and did not determine whether any single patient showed evidence of testicular dysfunction. Thus our data suggest that GH does not systematically affect testicular function; idiosyncratic effects would best be assessed by large-scale studies in which individual data can be analyzed.20 There was no significant difference in the pace of adrenarche between the GH-treated and control groups as defined by the progression in DHEA-S levels. In other circumstances, GH may affect adrenarche. Children with GH deficiency often have low levels 409
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of adrenal androgens. However, Sklar et al 21 found no change in DHEA-S levels in patients with GH deficiency after 6 months of GH therapy. Other case reports have suggested that GH excess may result in premature adrenarche.22 Many different regimens of GH administration have been used for the treatment of non-GH-deficient short stature. Our study evaluated the effects of GH therapy initiated in peripubertal boys and administered 3 times per week at one particular dose. The findings might not be generalizable to higher doses, more frequent administration, earlier initiation of therapy, or to girls without GH deficiency. However, for the treatment regimen evaluated, this randomized, double-blind, placebo-controlled study suggests that GH therapy does not affect the onset or pace of puberty, adult testicular function, or the pace of adrenarche in boys with non-GH-deficient short stature.
THE JOURNAL OF PEDIATRICS MARCH 2001
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5.
6.
7.
8.
9.
REFERENCES 1. Cuttler L, Silvers JB, Singh J, Marrero U, Finkelstein B, Tannin G, et al. Short stature and growth hormone therapy. A national study of physician recommendation patterns. JAMA 1996;276:531-7. 2. Hindmarsh PC, Brook CGD. Final height of short normal children treated with growth hormone. Lancet 1996; 348:13-6. 3. Kawai M, Momoi T, Yorifuji T, Yamanaka C, Sasaki H, Furusho K. Unfavorable effects of growth hormone therapy on the final height of boys with
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short stature not caused by growth hormone deficiency. J Pediatr 1997; 130:205-9. Hopwood NJ, Hintz RL, Gertner JM, Attie KM, Johanson AJ, Baptista J, et al. Growth response of children with non-growth-hormone deficiency and marked short stature during three years of growth hormone therapy. J Pediatr 1993;123:215-22. Darendeliler F, Hindmarsh PC, Preece MA, Cox L, Brook CGD. Growth hormone increases rate of pubertal maturation. Acta Endocrinol 1990;122:414-6. Price DA. Puberty in children with idiopathic growth hormone deficiency on growth hormone treatment: preliminary analysis of the data from the Kabi Pharmacia International Growth Study. 1991;379:117-24. Wilson ME, Gordon TP, Rudman CG, Tanner JM. Effects of growth hormone on the tempo of sexual maturation in female rhesus monkeys. J Clin Endocrinol Metab 1989;68:29-38. Wilson ME, Tanner JM. Long-term effects of recombinant human growth hormone treatment on skeletal maturation and growth in female rhesus monkeys with normal pituitary function. J Endocrinol 1991;130:435-41. Wilson ME. Administration of IGF-I affects the GH axis and adolescent growth in normal monkeys. J Endocrinol 1997;153:327-35. Wilson ME. Premature elevation in serum insulin-like growth factor-I advances first ovulation in rhesus monkeys. J Endocrinol 1998;158:247-57. Bertelloni S, Baroncelli GI, Viacava P, Massimetti M, Simi P, Saggese G. Can growth hormone treatment in boys without growth hormone deficiency impair testicular function? J Pediatr 1999;135:367-70. Zachmann M, Prader A, Kind HP, Hafliger H, Budliger H. Testicular volume during adolescence: cross-section-
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al and longitudinal studies. Helv Paediatr Acta 1974;29:61-72. Greulich WW, Pyle SI. Radiographic atlas of skeletal development of the hand and wrist. 2nd ed. Stanford (CA): Stanford University Press; 1959. Nieschlag E, Loriaux DL. Radioimmunoassay for plasma testosterone. Z Klin Chem Biochem 1972;10:164-8. Odell WD, Ross GT, Rayford PL. Radioimmunoassay for luteinizing hormone in human plasma or serum: physiological studies. J Clin Invest 1967;46:248-55. Cargille CM, Rayford PL. Characterization of antisera for human folliclestimulating hormone radioimmunoassay. J Lab Clin Med 1970;75:1030-40. Cutler GB Jr, Glenn M, Bush M, Hodgen GD, Graham CE, Loriaux DL. Adrenarche: a survey of rodents, domestic animals, and primates. Endocrinology 1978;103:2112-8. McCaughey ES, Mulligan J, Voss LD, Betts PR. Randomised trial of growth hormone in short normal girls. Lancet 1998;351:940-4. Loche S, Cambiaso P, Setzu S, Carta D, Marini R, Borrelli P, et al. Final height after growth hormone therapy in non-growth-hormone-deficient children with short stature. J Pediatr 1994;125:196-200. Frasier SD. A red flag unfurled? Growth hormone treatment and testicular function. J Pediatr 1999;135: 278-9. Sklar CA, Ulstrom RA. Effect of human growth hormone on adrenal androgens in children with growth hormone deficiency. Horm Res 1984; 20:166-71. Iwatani N, Kodama M, Seto H. A child with pituitary gigantism and precocious adrenarche: does GH and/or PRL advance the onset of adrenarche? Endocrinol Jpn 1992;39:251-7.
Objective: To evaluate the effect of growth hormone (GH) therapy on pubertal onset, pubertal pace, adult testicular function, and adrenarche in boys with non-GH-deficient short stature. Study design: Randomized, double-blind, placebo-controlled trial. GH (0.074 mg/kg, subcutaneously, 3 times per week) or placebo treatment was initiated in prepubertal or early pubertal boys and continued until near final height was reached (n = 49). Statistical significance was assessed by survival analysis, repeated-measures analysis of variance, and Student t test. Results: GH therapy did not affect the age at pubertal onset, defined either by testicular volume >4 mL or by testosterone concentration >1.0 nmol/L (30 ng/dL). GH treatment also did not affect the pace of puberty, defined either by the rate of change in testicular volume or testosterone concentration during the 4 years after pubertal onset. In boys followed up to age ≥16 years during the study, there were no significant differences in final testicular volume or in plasma testosterone, luteinizing hormone, or follicle-stimulating hormone concentrations. The pace of adrenarche, assessed by change in dehydroepiandrosterone sulfate levels over time, also did not differ significantly between the GH and placebo groups. Conclusion: Our findings suggest that GH treatment does not cause testicular damage, alter the onset or pace of puberty, or alter the pace of adrenarche in boys with non-GH-deficient short stature. (J Pediatr 2001;138:406-10)
From Developmental Endocrinology Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland; Biometry and Mathematical Statistics Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland; Department of Pediatrics, University of Tennessee Health Sciences Center, Memphis; and Eli Lilly and Company, Indianapolis, Indiana.
Drs Yanovski and Baron are Commissioned Officers in the United States Public Health Service. Supported in part by Eli Lilly and Co. Submitted for publication Mar 17, 2000; revision received June 30, 2000; accepted Aug 30, 2000. Reprint requests: Ellen Leschek, MD, DEB/NICHD, National Institutes of Health, Building 10, Room 10N262, 10 Center Dr, MSC 1862, Bethesda, MD 20892-1862. 9/21/111332 doi:10.1067/mpd.2001.111332
406
Growth hormone is often used to treat children with non-GH-deficient short stature1 despite the absence of any definitive, long-term, well-controlled studies of efficacy. Long-term studies lacking concurrent controls have yielded conflicting results as to whether GH therapy increases the final height of children without GH deficiency. Some of these studies suggest that GH may accelerate puberty, thus causing earlier epiphyseal fusion and offsetting the positive effects of GH.2-4 GH administration may also accelerate puberty in children with GH deficiency and nonhuman primates.5-10 DHEA-S FSH GH LH TV
Dehydroepiandrosterone sulfate Follicle-stimulating hormone Growth hormone Luteinizing hormone Testicular volume
In contrast, a recent case-report series suggests that GH may cause testicular damage in boys with non-GH-deficient short stature. Bertelloni et al11 described 4 men (aged 17-25 years) with hypergonadotropic hypogonadism who had previously received GH as children. Evidence suggesting hypogonadism included low testicular volume (4 of 4 patients, mean = 11 mL), low serum testosterone concentration (1 patient), elevated basal follicle-stimulating hormone levels (4 patients), elevated basal luteinizing hormone levels (3 patients), and de-
LESCHEK ET AL
THE JOURNAL OF PEDIATRICS VOLUME 138, NUMBER 3 Table I. Clinical characteristics of the subjects at initiation of treatment*
Pubertal onset
Pubertal pace
Testicular function
All subjects
Analysis
Placebo
GH
Placebo
GH
Placebo
GH
Placebo
GH
No. of subjects Chronological age (y) Bone age (y) TV (mL)
12 11.5 ± 0.4 10.2 ± 0.5 3.4 ± 1.0
11 12.0 ± 0.5 10.1 ± 0.5 3.1 ± 0.5
13 12.2 ± 0.4 10.7 ± 0.4 3.7 ± 0.4
15 12.7 ± 0.4 10.7 ± 0.5 3.6 ± 0.3
13 13.3 ± 0.3 11.7 ± 0.3 7.0 ± 1.2
19 13.2 ± 0.4 11.2 ± 0.4 5.5 ± 0.7
24 12.3 ± 0.3 10.9 ± 0.3 4.9 ± 0.8
25 12.8 ± 0.3 10.9 ± 0.4 4.9 ± 0.6
Values are expressed as mean ± SEM. GH, Growth hormone; TV, testicular volume. *Different subsets of subjects were used for different analyses (age at pubertal onset, pubertal pace, testicular function at completion of treatment).
creased sperm concentration and motility (4 patients). These possible effects of GH therapy on the timing of puberty and on testicular function have been proposed based on case-report series and on clinical trials lacking concurrent, randomized control groups. To evaluate these issues more rigorously, we evaluated the effects of GH administration on: (1) the age at pubertal onset, (2) the pace of pubertal progression, (3) testicular function after completion of puberty, and (4) the pace of adrenarche in males without GH deficiency enrolled in a randomized, double-blind, placebocontrolled trial of GH therapy.
METHODS Subjects Subjects were participating in a randomized, double-blind, placebo-controlled trial of GH for non-GH-deficient short stature, which has been ongoing since 1987. Inclusion criteria at entry were (1) age 10 to 16 years, (2) bone age ≤13 years, (3) testicular volume ≤10 mL, (4) proportionate short stature with absolute and/or predicted height ≤–2.5 SD for age, and (5) peak stimulated GH ≥7 ng/mL. Subjects were excluded if they had a chronic illness or a known genetic syndrome or were receiving any medications likely to affect growth. The current analysis was restricted to male subjects. Table I shows the clinical characteristics of the subjects at initiation of treatment.
Table II. Age (mean ± SEM) at pubertal onset defined by TV >4 mL or by testosterone concentration >1.0 nmol/L (30 ng/dL)
Age at pubertal onset (y) Criterion
Placebo
GH
TV >4 mL Testosterone >1.0 nmol/L
13.5 ± 0.5 13.5 ± 0.6
13.3 ± 0.5 14.1 ± 0.4
GH, Growth hormone; TV, testicular volume.
Protocol The protocol was approved by the Institutional Review Board of the National Institute of Child Health and Human Development. Informed consent was obtained from a parent, and assent was given by each child. Subjects were evaluated every 6 months, starting 6 months before the initiation of treatment. At each visit, LH, FSH, testosterone, and dehydroepiandrosterone sulfate concentrations were measured 3 times at 20-minute intervals. TV was measured with a Prader orchidometer,12 and bone age was determined by the method of Greulich and Pyle.13 Treatment with either GH (Humatrope [Eli Lilly and Company, Indianapolis, Ind], 0.074 mg/kg injected subcutaneously 3 times per week) or placebo was started 6 months after enrollment and continued until near final height was reached. This dose and frequency were selected because they represent regimens commonly used at the time of study design. To avoid compromising this ongoing, double-blind study examining the effect of GH on
adult height, no variables involving growth were examined. Individual data were available only to a collaborating statistician (J.F.T.).
Hormone Assays LH, FSH, testosterone, and DHEAS concentrations were measured by radioimmunoassay (Covance Laboratories, Vienna, Va).14-17
Statistical Analysis Results were expressed as mean ± SEM. For the analysis of pubertal onset, subjects were included if they were prepubertal (TV ≤4 mL or testosterone concentration ≤1.0 nmol/L [30 ng/dL], depending on the analysis) at the initiation of treatment. Survival analysis was used to examine these data. Tests of equality of survival curves were performed by the log-rank test provided by Proc Lifetest in the SAS statistical software package (SAS Institute Inc, Cary, NC). For the analysis of pubertal pace, subjects were included if they were prepubertal at the initial evaluation and started pu407
LESCHEK ET AL
A
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B
Fig 1. Pace of puberty as defined by testicular volume (A, n = 29) or by plasma testosterone concentration (B, n = 28) in subjects receiving GH (solid circles, solid lines) or placebo (open circles, dashed lines). Symbols and error bars represent mean ± SEM.
and treatment on DHEA-S values were assessed by repeated-measures analysis of variance, including a term for initial bone age deficit.
RESULTS Age at Pubertal Onset
Fig 2. Pace of adrenarche as defined by mean ± SEM plasma DHEA-S concentration in subjects (n = 35) receiving GH (solid circles, solid line) or placebo (open circles, dashed line).
In the boys who were prepubertal at the start of the study, GH did not affect the age at onset of puberty, defined either by TV >4 mL or by testosterone concentration >1.0 nmol/L (30 ng/dL) (Table II). The duration of treatment before pubertal onset was 1.6 ± 0.2 years versus 2.3 ± 0.3 years (GH vs placebo).
Pace of Pubertal Progression berty (TV >4 mL) during the study. Data from the first 4 years after onset of puberty were included. Pubertal pace was assessed by repeated-measures analysis of variance with the use of the Proc Mixed program in the SAS software package. Correlation between observations on the same patient was assumed to decline with increase in time difference between the observations. The models included terms for age at onset of puberty and initial bone age deficit (bone age minus 408
chronological age). For the analysis of testicular function after completion of puberty, subjects were included if they were ≥16 years of age at the time of analysis. The final measurements obtained for each subject were analyzed by Student t test to compare the GH and placebo groups. If a statistically significant difference in variance was found by F test, the approximate t test with the df of Satterthwaite was used. For the analysis of adrenarche, all subjects were included. The effects of age
We analyzed the rate of pubertal progression during the 4 years after the onset of puberty (defined by TV >4 mL). GH treatment did not affect the rate of increase of TV (4.1 ± 0.3 vs 4.1 ± 0.3 mL/y, GH vs placebo, n = 29, P = NS, Fig 1, A) or the rate of increase in testosterone (5.44 ± 0.83 vs 5.41 ± 0.87 nmol/L/y [157 ± 24 vs 156 ± 25 ng/dL/y], n = 28, P = NS, Fig 1, B). TV ≥15 mL was achieved at 15.5 ± 0.4 years of age in the GH-treated group and 15.3 ± 0.4 years of age in the placebo-treated group.
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Table III. Testicular volume and function (mean ± SEM) at completion of treatment and at least 1 year after completion of treatment
Completion of treatment
Age (y) Duration of treatment (y) TV (mL) Testosterone (nmol/L) (ng/dL) LH (IU/L) FSH (IU/L)
One year after completion of treatment
Placebo
GH
Placebo
GH
17.5 ± 0.2 4.2 ± 0.3 20.9 ± 0.8 20.4 ± 1.4 587 ± 41 10.7 ± 0.7 9.2 ± 1.0
17.8 ± 0.3 4.6 ± 0.3 20.7 ± 0.8 20.9 ± 1.6 603 ± 47 11.8 ± 1.2 8.9 ± 1.4
18.9 ± 0.4
19.4 ± 0.4
22.5 ± 1.6 28.8 ± 3.5 832 ± 101 11.3 ± 1.1 8.8 ± 1.0
20.9 ± 1.3 20.5 ± 1.0 592 ± 29 13.9 ± 2.6 11.1 ± 2.8
None of the differences between treatment groups were statistically significant. GH, Growth hormone; TV, testicular volume; LH, luteinizing hormone; FSH, follicle-stimulating hormone.
Testicular Volume and Function After Completion of Puberty In boys who were followed up to age ≥16 years during the study (n = 32), there were no significant differences between treatment groups in final TV or testosterone, LH, or FSH levels. Fifteen of the subjects included in this analysis were evaluated at least 1 year after discontinuation of therapy, and at that time, there were still no significant differences between treatment groups in TV or testosterone, LH, or FSH levels (Table III).
Pace of Adrenarche Adrenarche was evaluated in all boys who were followed up in the study. GH treatment did not affect the pace of adrenarche (n = 35), defined by the rate of change in DHEA-S concentration (0.69 ± 0.13 vs 0.76 ± 0.14 µmol/L/y [25.5 ± 4.7 vs 28.0 ± 5.3 µg/dL/y], GH vs placebo, P = NS, Fig 2).
DISCUSSION In boys with non-GH-deficient short stature, GH treatment did not significantly alter the age at pubertal onset, defined either by TV or by serum testosterone concentration. GH therapy also did not alter the pace of puberty, defined either by the rate of testicular growth or the rate of increase in serum testosterone.
Previous studies of children without GH deficiency treated with GH have yielded conflicting results. In some studies, the onset and pace of puberty were reportedly unaffected by GH administration.18,19 Other reports suggest that GH therapy may hasten the onset of puberty3 and/or accelerate the pace of puberty2-4 in boys with nonGH-deficient short stature. Kawai et al3 reported that GH treatment (at doses ~80% of that used in the current study) accelerates both the onset and pace of puberty in males with nonGH-deficient short stature. In contrast to these studies, our study had a doubleblind, placebo-controlled, randomized design. The only previous randomized trial to address this issue differed from our study in that the subjects were girls, the control group was untreated, and the number of subjects studied was smaller. In that study, McCaughey et al18 found that GH did not affect pubertal onset or pace. At completion of puberty and at least 1 year after the completion of treatment, there were no significant differences between the GH and placebo groups in terms of TV or plasma testosterone, LH, or FSH concentrations. Thus GH treatment did not appear to cause testicular injury. Recently, Bertelloni et al11 described 4 males without GH deficiency (ranging in age from 17 to 25 years) who developed hypergonadotropic hypogonadism
after receiving GH therapy as children (duration of treatment ranged from 4.3 to 12.4 years). The GH dose received by these patients (0.6-1.0 IU/kg/wk) was comparable to that used in the current study, but the frequency of administration (6 times per week) was greater. The median age at which these 4 patients were evaluated (18.8 years) was similar to that in the current study. Our findings suggest that the testicular dysfunction in these patients may not have been caused by GH but rather may have been caused by an underlying disorder that resulted in both short stature and hypergonadotropic hypogonadism. However, our data cannot exclude the possibility that testicular injury could be a rare, idiosyncratic reaction to GH treatment. To preserve the integrity of the double-blind trial design, we analyzed only grouped data and did not determine whether any single patient showed evidence of testicular dysfunction. Thus our data suggest that GH does not systematically affect testicular function; idiosyncratic effects would best be assessed by large-scale studies in which individual data can be analyzed.20 There was no significant difference in the pace of adrenarche between the GH-treated and control groups as defined by the progression in DHEA-S levels. In other circumstances, GH may affect adrenarche. Children with GH deficiency often have low levels 409
LESCHEK ET AL
of adrenal androgens. However, Sklar et al 21 found no change in DHEA-S levels in patients with GH deficiency after 6 months of GH therapy. Other case reports have suggested that GH excess may result in premature adrenarche.22 Many different regimens of GH administration have been used for the treatment of non-GH-deficient short stature. Our study evaluated the effects of GH therapy initiated in peripubertal boys and administered 3 times per week at one particular dose. The findings might not be generalizable to higher doses, more frequent administration, earlier initiation of therapy, or to girls without GH deficiency. However, for the treatment regimen evaluated, this randomized, double-blind, placebo-controlled study suggests that GH therapy does not affect the onset or pace of puberty, adult testicular function, or the pace of adrenarche in boys with non-GH-deficient short stature.
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