- Email: [email protected]
Insulin Resistance and Adolescent Girls with Polycystic Ovary Syndrome
J Pediatr Adolesc Gynecol (2010) 23:158e161
Original Study Insulin Resistance and Adolescent Girls with Polycystic Ovary Syndrome S.M. Bhattacharya, MD1 and M. Ghosh, MD, MBBS2 1
S.C. Das Memorial Medical & Research Center and Vivekananda Institute of Medical Sciences, Kolkata, India; 2Department of Pharmacology, R.G. Kar Medical College, Kolkata, India
Abstract. Study Objectives: To estimate (1) the prevalence of insulin resistance (IR), by fasting glucose: insulin ratio (G:I ! 7.0) in adolescent girls with polycystic ovary syndrome (PCOS), (2) to compare the clinical and biochemical parameters between insulin-resistant and non-insulin resistant groups. Design: Case series. Setting: Clinic based. Participants: 49 adolescent girls with complaints of oligomenorrhoea with hirsutism and or acne. Interventions: Forty-nine adolescent girls diagnosed to have PCOS (Rotterdam 2003 criteria) were studied. Body mass index (BMI), abdominal circumference (AC), hirsutism (Ferriman Gallway score $ 6), presence of acne, acanthosis nigricans (AN) were noted in each case. Serum testosterone, sex hormone binding globulin (SHBG), fasting plasma glucose and insulin levels were measured. Free androgen index (FAI) was calculated. Results: 69.4% of these girls were found to have IR. There were no differences in age, BMI, AC, serum testosterone, FAI and fasting glucose levels between insulin resistant and noninsulin resistant girls. But there were significant differences in frequencies of hirsutism, acne, AN, and serum levels of SHBG and fasting insulin between the two groups. Conclusion: Adolescent girls with PCOS and IR are more hirsute and have more AN and lower SHBG and higher fasting insulin levels compared to non-insulin resistant girls.
Introduction
affecting women. ‘Normal’ adolescence is accompanied by some of the recognized symptoms of PCOS like menstrual irregularities and acne. Oligomenorrhoea in adolescence is also regarded as a ‘normal’ stage in the physiological maturation of the hypothalamo-pituitary-ovarian axis. The role of insulin resistance (IR) in the pathogenesis of PCOS has gained much importance for quite some time. Insulin resistance is defined as an impaired biological response to either exogenous or endogenous insulin.1 The measured biological response could reflect, in theory, metabolic processes (changes in carbohydrate, lipid or protein metabolism), as well as mitogenic processes (alterations in growth, differentiation, DNA synthesis, regulation of gene transcription).1 For many years, the gold standard for assessing insulin sensitivity has been the hyperinsulinemiceuglycemic clamp technique. It is an accurate in vivo assessment of insulin action, but it is expensive, invasive, and uncomfortable for the patient, and also timeconsuming.2 As a result, simple and accurate methods to assess insulin sensitivity, like fasting glucose to insulin ratio (G:I), have been developed. The fasting G:I ratio as a simple measure of IR in PCOS women has been correlated well with more complicated dynamic tests of insulin action.3 Legro4 found that a fasting glucose/insulin ratio less than 7.0 is suggestive of insulin resistance in adolescent PCOS girls. The aim of this study is to estimate the prevalence of IR (detected by fasting glucose/insulin ratio !7.0) among adolescent girls with PCOS and to compare the clinical and biochemical parameters between insulin-resistant and noneinsulin-resistant groups.
Polycystic ovary syndrome (PCOS) is one of the most common gynecological endocrinological disorders
Materials and Methods
Address correspondence to: Prof. S.M. Bhattacharya, Flat-4. Mohona, 5, New Raipur, Kolkata-700084, India; E-mail: [email protected]
Forty-nine girls in the age group of 12e19 years attended the author’s clinic at S.C. Das Memorial Medical and Research Center, between June 2006
Ó 2010 North American Society for Pediatric and Adolescent Gynecology Published by Elsevier Inc.
1083-3188/$36.00 doi:10.1016/j.jpag.2009.10.004
Key Words. Insulin resistance—Adolescence— Polycystic ovary syndrome
Bhattacharya and Ghosh: Insulin Resistance in Girls with PCOS
and May 2008, with the complaints of oligomenorrhoea (#6 menses per year) with clinical evidence of hyperandrogenism (hirsutism and/or acne). They underwent detailed clinical examination and hormonal tests, as mentioned below, for the diagnosis of PCOS (as per the Rotterdam 2003 criteria).5 The Institutional Ethics Committee approved the study. A parent of each adolescent girl gave consent to the study and also for the utilization of the data for this study. Secondary causes of hyperandrogenism, such as 21-hydroxylase deficiency, Cushing syndrome, hypothyroidism, hyperprolactinemia, and androgensecreting tumor, were excluded by appropriate clinical and/or laboratory tests. Rotterdam criteria5 state that for the diagnosis of PCOS, any two of the following three criteria should be fulfilled, with exclusion of other etiologies (congenital adrenal hyperplasia, androgen secreting tumors, Cushing’s syndrome): 1. Oligo- or anovulation. 2. Clinical and/or biochemical signs of hyperandrogenism. 3. Polycystic ovaries. During clinical examination, height of every girl was recorded to the nearest 0.5 cm, and weight was taken on a platform scale, the accuracy of which was checked each time before weighing. The weight was recorded in kg with minimum garments on the subject. Body mass index (BMI) (kg/m2) was calculated in each case from height and weight measurements. Abdominal circumference (AC) of every girl was recorded, as recommended by Legro et al.6 Hirsutism scoring was done as per the modified Ferriman-Galway score (mFG score). Nine body areas were scored from 0e4 for terminal hair growth distribution. The mFG score of $6 of facial and body terminal hair growth was considered as hirsutism.7 Presence of acne and acanthosis nigricans (AN) was noted in each case. Transabdominal ultrasonography was done to note the status of the ovaries. In India, vaginal ultrasonography is not done in unmarried girls for social reasons. The following biochemical tests were done: serum total testosterone level; sex hormone binding globulin (SHBG) level; insulin level and plasma glucose level (after 8e10 hours fasting). These hormonal tests were done on the second/third day of a progestogeninduced bleeding. The Free Androgen Index (FAI) was calculated by the following formula: FAI 5 Testosterone (nmol/l)/SHBG (nmol/l) 100. Insulin was measured by Elecsys 2010, Roche Lot No. 179-202-01. SHBG was measured by ELISA technique (EIA-2996) [DRG instruments Gmbh, Germany]. Plasma glucose was measured by Glucose oxidase-peroxidase method (Roche Diagnostics Gmbh, Mannheim, Germany). Serum testosterone
159
was measured by Electrochemiluminescence Immunoassay, Roche Lot. No. 181371-01(Roche Diagnostics Gmbh, Mannheim, Germany. Exclusion Criteria 1. Girls with hyperprolactinemia/hypothyroidism. 2. Girls with secondary causes of androgen excess. 3. Girls who had any hormone treatment in the preceding three months—to avoid inaccuracy in the assessment of circulating androgen/SHBG levels. 4. Girls with gynecological age less than 3 years. These studied cases were divided into two groups: Group A: 34 cases with fasting G:I ratio ! 7.0 (insulin-resistant group). Group B: 15 cases with fasting G:I ratio $ 7.0 (noneinsulin-resistant group). Statistical Analysis Assuming a confidence level of 95%, with a sample size of 49, calculated confidence interval was 14%. For comparison of various clinical and biochemical parameters, all parameters was tested for normality pre-test (using Kolmogorov-Smirnov), and in cases in which at least one group failed, the non-parametric Mann-Whitney U test, unless otherwise specified, was done. For comparison of incidence of hirsutism, acne, and AN, the chi-square test was used. P ! 0.05 was considered as significant. Results Table 1 shows the prevalence of IR in adolescent PCOS girls, on the basis of fasting G:I ratio. Of the 49 cases, 34 (69.4%) of cases (Group A) were found to be insulin resistant (Group A) and 15 (30.6%) were non-insulin resistant (group B). Table 2 shows the values of the clinical parameters studied and the differences between the two groups of girls. There were no differences in age, BMI and AC. Frequencies of hirsutism (P 5 0.01), acne (P ! 0.01) and AN (P 5 0.0004) showed significant differences. Table 3 shows the values of the biochemical parameters studied, and the differences in these parameters between the two groups. There were no differences in serum testosterone levels, FAI values and fasting sugar values. Significant differences were noted in SHBG levels (P 5 0.04) and fasting insulin levels (P # 0.0001). Discussion This study was done on 49 adolescent Indian girls with PCOS. There are many studies on insulin resistance in adult PCOS women but scant studies have been done on adolescent girls with PCOS in India.
160
Bhattacharya and Ghosh: Insulin Resistance in Girls with PCOS
Table 1. Prevalence of Insulin Resistance in Adolescent PCOS Girls, Calculated on the Basis of Fasting G:I Ratio
Table 3. Biochemical Parameters of the Two Groups
Fasting G:I ratio
Parameters
Group A Mean (SD)
Group B Mean (SD)
Testosterone level (ng/ml) SHBG (nmol/l) FAI Fasting sugar [mg (%)] Fasting insulin (mu/ml)
0.44 21.9 8.5 89.9 22.6
0.53 30.9 7.8 87.4 8.6
Number of Cases
%
34 15
69.4 30.6
! 7.0 $7.0
The implications of insulin resistance in the context of a typical Indian diet rich in carbohydrates remain to be explored. Adolescents are much less concerned about, and probably unaware of, the long-term sequelae of hyperandrogenism, often accompanied by hyperinsulinemia, which are now coming to light and may threaten their general health after age 40.8 A fasting G:I ratio of less than 7.0 was considered to indicate IR in these girls.4 IR can be an intrinsic defect in PCOS women.5,9,10 Biochemical features such as increased androgen and insulin secretion, typical of PCOS, are also often a feature of a normal adolescence. So the biochemical markers for PCOS can be inconsistent in adolescence.8 It is likely that body fat distribution plays an important role in PCOS women and that their IR is connected very tightly with upper body adiposity.11 This study in adolescent girls shows that the BMI and AC were not significantly different between the insulin-resistant and noneinsulin-resistant groups, calculated upon the basis of fasting G:I ratio. These do not accord well with the results of other authors done on adults.10,12 Dunaif 13 reported the presence of intense insulin resistance in adolescents with PCOS regardless of body composition or abdominal obesity. In clinical practice, abdominal circumference is measured as a surrogate measure of visceral fat. Visceral fat, also called central or abdominal fat, is metabolically distinct from subcutaneous fat. It is resistant to the antilipolytic effects of insulin and releases excessive amounts of free fatty acids. These free fatty acids lead to IR in liver and the muscle. In response to it, in the liver, there is increased Table 2. Clinical Parameters of the Two Groups of PCOS Girls Parameters Age (years) BMI (kg/m2) AC (cm) Hirsutism present (FG score 5 O6) Acne present AN present
Group A Mean (SD) Group B Mean (SD) 16.7 (1.8) 26.8 (4.1) 80.2 (9.5) n (%) 15 (44.1)* 21 (61.7)** 20 (58.8)***
*P 5 0.01. **P ! 0.01. ***P 5 0.0004, chi-square test.
17.4 (1.3) 25.8 (4.4) 77.5 (10.0) n (%) 4 (26.6) 12 (80.0) 5 (33.3)
(0.3) (13.3) (6.2) (9.1) (9.5)
(0.3) (14.7)* (7.2) (7.3) (3.1)**
*P 5 0.04, compared to group A. **P 5 0.0001, compared to group A.
gluconeogenesis, and in the muscle there is inhibition of insulin mediated glucose uptake.14e16 Excess fat itself contributes to IR at the level of the adipocyte. When fat cells become too large, they are unable to store additional lipids. Fat is then stored in the muscle, liver, and beta cells of the pancreas, which also contributes to IR in these organs. Visceral fat also produces excess 11-beta-hydroxysteroid dehydrogenase1, an enzyme that converts inactive cortisone to the biochemically active cortisol. This cortisol can promote central adiposity and IR.17 The present study found significant differences in the incidences of hirsutism and AN between insulin resistant and non-insulin resistant girls with PCOS. AN is a clinical parameter which has been found to be independently associated with hyperinsulinemia and, therefore, may be useful as an early indicator of high risk for diabetes.18 This study shows that non-insulin resistant girls had significantly higher incidence of acne compared to insulin resistant girls. But the lower absolute size of this group needs to be taken into account while interpreting this result. Acne is common in adolescence and may not always be due to PCOS. It has been correlated with an increase in dehydroepiandrosterone sulfate (DHEAS) and does not necessarily indicate an abnormal ovulatory mechanism in these adolescent girls.19 The present study did not find any difference in serum total testosterone levels and in FAI values between the two groups. But there were significant differences in SHBG and fasting insulin levels. This shows that neither serum testosterone level nor FAI values can predict or detect IR in adolescent PCOS girls. Luteinizing hormone (LH) and other androgens such as DHEA-sulphate have not been measured in this study. Role of LH and adrenal gland secretion in adolescent PCOS girls need further studies. It has been reported that hyperandrogenism, not necessarily solely due to testosterone, can affect the cellular mechanism of insulin action, stimulating the beta cells of the pancreas to produce more insulin leading to IR.12 The significantly high serum insulin level in insulin-resistant PCOS girls and the state of hyperandrogenism at the cellular level is a matter of great interest.
Bhattacharya and Ghosh: Insulin Resistance in Girls with PCOS
Insulin along with insulin-like growth factor-1 can stimulate the follicular theca to produce ovarian androgens.20 Therefore, this study shows that adolescent PCOS girls who have insulin resistance do not have higher BMI or higher AC, but do have greater incidences of hirsutism and AN, compared to non-insulin resistant adolescent PCOS girls. Thus, two simple clinical parameters, namely hirsutism and AN, will help the clinician to suspect the underlying metabolic abnormalities in adolescent girls with PCOS. Studies have reported a positive correlation between low SHBG and insulin secretion and peripheral glucose utilization.21 The present study finds that the SHBG and insulin levels are significantly different between the two groups. It remains to be determined whether low SHBG levels are indicative of hyperinsulinemia and insulin resistance and this would help define patients at risk for PCOS.22 It is important to note that this study has the limitations of a case series in design and restricted number of clinical/biochemical parameters investigated. Since this is a clinic-based study, fasting G:I ratio was used to detect IR instead of hyperinsulinemic-euglycemic clamp technique. The role of adrenal steroids and desynchronization of LH and FSH secretion from the pituitary gland in the pathogenesis of insulin resistance in adolescent PCOS girls needs more study. Summary and Conclusion Forty-nine adolescent PCOS girls have been studied. Insulin resistance was found in 69.4% of cases by fasting glucose: insulin ratio. There are no differences in BMI, AC, serum testosterone and fasting plasma glucose levels between insulin-resistant and noneinsulin-resistant adolescent girls. There are significant differences in SHBG and fasting insulin levels between the two groups. Insulin resistance in adolescent PCOS girls is associated with significant increase in incidences of hirsutism and acanthosis nigricans. References 1. American Diabetes Association: Consensus Development Conference on Insulin Resistance. Diabetes Care 1998; 21:310 2. DeFronzo RA, Tobin JD, Andres R: Glucose clamp technique: a method for quantifying insulin secretion and resistance. Am J Physiol 1979; 237:E214 3. Legro RS, Finegood D, Dunaif A: A fasting glucose to insulin ratio is a useful measure of insulin sensitivity in women with polycystic ovary syndrome. J Clin Endocrinol Metab 1999; 83:2694 4. Legro RS: Detection of insulin resistance and its treatment in adolescents with polycystic ovary syndrome. J Pediatr Endocrinol Metab 2002; 15(Suppl 5):1367
161
5. Rotterdam ESHRE/ASRM-sponsored PCOS consensus workshop group: Revised 2003 consensus on diagnostic criteria and long-term health risks related to polycystic ovary syndrome (PCOS). Hum Reprod 2004; 9:41 6. Legro RS, Kunselman AR, Dodson WC, et al: Prevalence and predictors of risk for Type 2 diabetes mellitus and impaired glucose tolerance in polycystic ovary syndrome: a prospective controlled study in 254 affected women. J Clin Endocrinol Metab 1999; 84:165 7. Lewis V: Polycystic ovary syndrome: a diagnostic challenge. Obstet Gynecol Clin N Am 2003; 14:197 8. Homburg R, Lambalk BC: Polycystic ovary syndrome in adolescenceea therapeutic conundrum. Hum Reprod 2004; 19:1039 9. Gennarelli G, Holte J, Berglund L, et al: Prediction model for insulin resistance in the polycystic ovary syndrome. Hum Reprod 2000; 15:1098 10. Morin-Papunen LC, Vauhkomen I, Koivunen RM, et al: Insulin sensitivity, insulin secretion and metabolic and hormonal parameters in healthy women and women with polycystic ovary syndrome. Hum Reprod 2000; 15:1266 11. Holte J: Polycystic ovary syndrome and insulin resistance: thrifty genes struggling with over-feeding and sedentary life style? J Endocrinol Invest 1998; 21:589 12. Vrbikova´ J, Bendlova´ B, Hill M, et al: Insulin sensitivity and beta cell function in women with polycystic ovary syndrome. Diabetes Care 2002; 25:1217 13. Dunaif A: Insulin resistance and the polycystic ovary syndrome: mechanism and implications for pathogenesis. Endocr Rev 1997; 18:774 14. Nesto R: C-reactive protein, its role in inflammation, Type 2 diabetes and cardiovascular disease, and the effects of insulin-sensitizing treatment with thiazolidinediones. Diabet Med 2004; 21:810 15. Bays H, Mandarino L, DeFronzo RA: Role of the adipocyte, free fatty acids, and ectopic fat in the pathogenesis of type 2 diabetes mellitus: peroxisomal proliferatoractivated receptor agonists provide a rational therapeutic approach. J Clin Endocrinol Metab 2004; 89:163 16. Hsueh WA, Lyon CJ, Quin˜ones MJ: Insulin resistance and the endothelium. Am J Med 2004; 117:109 17. Masuzaki H, Flier JS: Tissue-specific glucocorticoid reactivating enzyme, 11-beta-hydroxysteroid dehydrogenase type 1 (11 beta-HSD1)ea promising drug target for the treatment of metabolic syndrome. Curr Drug Targets Immune Endocr Metab Disord 2003; 3:255 18. Stuart CA, Gilkison CR, Smith MM, et al: Acanthosis nigricans as a risk factor for non-insulin dependent diabetes mellitus. Clin Paediatr 1998; 37:13 19. Jeffrey Chang R, Coffler MS: Polycystic ovary syndrome: early detection in the adolescent. Clin Obstet Gynecol 2007; 50:178 20. Fernandes AR, Japur de Sa´ Rosa e Silva AC, Roma¨o GS, et al: Insulin resistance in adolescents with menstrual irregularities. J Pediatr Adolesc Gynecol 2005; 18:269 21. Pugeat M, Cousin P, Baret C, et al: Sex hormone-binding globulin during puberty in normal and hyperandrogenic girls. J Pediatr Endocrinol Metab 2000; 13:1277 22. Driscoll DA: Polycystic ovary syndrome in adolescence. Semin Reprod Med 2003; 21:301
Original Study Insulin Resistance and Adolescent Girls with Polycystic Ovary Syndrome S.M. Bhattacharya, MD1 and M. Ghosh, MD, MBBS2 1
S.C. Das Memorial Medical & Research Center and Vivekananda Institute of Medical Sciences, Kolkata, India; 2Department of Pharmacology, R.G. Kar Medical College, Kolkata, India
Abstract. Study Objectives: To estimate (1) the prevalence of insulin resistance (IR), by fasting glucose: insulin ratio (G:I ! 7.0) in adolescent girls with polycystic ovary syndrome (PCOS), (2) to compare the clinical and biochemical parameters between insulin-resistant and non-insulin resistant groups. Design: Case series. Setting: Clinic based. Participants: 49 adolescent girls with complaints of oligomenorrhoea with hirsutism and or acne. Interventions: Forty-nine adolescent girls diagnosed to have PCOS (Rotterdam 2003 criteria) were studied. Body mass index (BMI), abdominal circumference (AC), hirsutism (Ferriman Gallway score $ 6), presence of acne, acanthosis nigricans (AN) were noted in each case. Serum testosterone, sex hormone binding globulin (SHBG), fasting plasma glucose and insulin levels were measured. Free androgen index (FAI) was calculated. Results: 69.4% of these girls were found to have IR. There were no differences in age, BMI, AC, serum testosterone, FAI and fasting glucose levels between insulin resistant and noninsulin resistant girls. But there were significant differences in frequencies of hirsutism, acne, AN, and serum levels of SHBG and fasting insulin between the two groups. Conclusion: Adolescent girls with PCOS and IR are more hirsute and have more AN and lower SHBG and higher fasting insulin levels compared to non-insulin resistant girls.
Introduction
affecting women. ‘Normal’ adolescence is accompanied by some of the recognized symptoms of PCOS like menstrual irregularities and acne. Oligomenorrhoea in adolescence is also regarded as a ‘normal’ stage in the physiological maturation of the hypothalamo-pituitary-ovarian axis. The role of insulin resistance (IR) in the pathogenesis of PCOS has gained much importance for quite some time. Insulin resistance is defined as an impaired biological response to either exogenous or endogenous insulin.1 The measured biological response could reflect, in theory, metabolic processes (changes in carbohydrate, lipid or protein metabolism), as well as mitogenic processes (alterations in growth, differentiation, DNA synthesis, regulation of gene transcription).1 For many years, the gold standard for assessing insulin sensitivity has been the hyperinsulinemiceuglycemic clamp technique. It is an accurate in vivo assessment of insulin action, but it is expensive, invasive, and uncomfortable for the patient, and also timeconsuming.2 As a result, simple and accurate methods to assess insulin sensitivity, like fasting glucose to insulin ratio (G:I), have been developed. The fasting G:I ratio as a simple measure of IR in PCOS women has been correlated well with more complicated dynamic tests of insulin action.3 Legro4 found that a fasting glucose/insulin ratio less than 7.0 is suggestive of insulin resistance in adolescent PCOS girls. The aim of this study is to estimate the prevalence of IR (detected by fasting glucose/insulin ratio !7.0) among adolescent girls with PCOS and to compare the clinical and biochemical parameters between insulin-resistant and noneinsulin-resistant groups.
Polycystic ovary syndrome (PCOS) is one of the most common gynecological endocrinological disorders
Materials and Methods
Address correspondence to: Prof. S.M. Bhattacharya, Flat-4. Mohona, 5, New Raipur, Kolkata-700084, India; E-mail: [email protected]
Forty-nine girls in the age group of 12e19 years attended the author’s clinic at S.C. Das Memorial Medical and Research Center, between June 2006
Ó 2010 North American Society for Pediatric and Adolescent Gynecology Published by Elsevier Inc.
1083-3188/$36.00 doi:10.1016/j.jpag.2009.10.004
Key Words. Insulin resistance—Adolescence— Polycystic ovary syndrome
Bhattacharya and Ghosh: Insulin Resistance in Girls with PCOS
and May 2008, with the complaints of oligomenorrhoea (#6 menses per year) with clinical evidence of hyperandrogenism (hirsutism and/or acne). They underwent detailed clinical examination and hormonal tests, as mentioned below, for the diagnosis of PCOS (as per the Rotterdam 2003 criteria).5 The Institutional Ethics Committee approved the study. A parent of each adolescent girl gave consent to the study and also for the utilization of the data for this study. Secondary causes of hyperandrogenism, such as 21-hydroxylase deficiency, Cushing syndrome, hypothyroidism, hyperprolactinemia, and androgensecreting tumor, were excluded by appropriate clinical and/or laboratory tests. Rotterdam criteria5 state that for the diagnosis of PCOS, any two of the following three criteria should be fulfilled, with exclusion of other etiologies (congenital adrenal hyperplasia, androgen secreting tumors, Cushing’s syndrome): 1. Oligo- or anovulation. 2. Clinical and/or biochemical signs of hyperandrogenism. 3. Polycystic ovaries. During clinical examination, height of every girl was recorded to the nearest 0.5 cm, and weight was taken on a platform scale, the accuracy of which was checked each time before weighing. The weight was recorded in kg with minimum garments on the subject. Body mass index (BMI) (kg/m2) was calculated in each case from height and weight measurements. Abdominal circumference (AC) of every girl was recorded, as recommended by Legro et al.6 Hirsutism scoring was done as per the modified Ferriman-Galway score (mFG score). Nine body areas were scored from 0e4 for terminal hair growth distribution. The mFG score of $6 of facial and body terminal hair growth was considered as hirsutism.7 Presence of acne and acanthosis nigricans (AN) was noted in each case. Transabdominal ultrasonography was done to note the status of the ovaries. In India, vaginal ultrasonography is not done in unmarried girls for social reasons. The following biochemical tests were done: serum total testosterone level; sex hormone binding globulin (SHBG) level; insulin level and plasma glucose level (after 8e10 hours fasting). These hormonal tests were done on the second/third day of a progestogeninduced bleeding. The Free Androgen Index (FAI) was calculated by the following formula: FAI 5 Testosterone (nmol/l)/SHBG (nmol/l) 100. Insulin was measured by Elecsys 2010, Roche Lot No. 179-202-01. SHBG was measured by ELISA technique (EIA-2996) [DRG instruments Gmbh, Germany]. Plasma glucose was measured by Glucose oxidase-peroxidase method (Roche Diagnostics Gmbh, Mannheim, Germany). Serum testosterone
159
was measured by Electrochemiluminescence Immunoassay, Roche Lot. No. 181371-01(Roche Diagnostics Gmbh, Mannheim, Germany. Exclusion Criteria 1. Girls with hyperprolactinemia/hypothyroidism. 2. Girls with secondary causes of androgen excess. 3. Girls who had any hormone treatment in the preceding three months—to avoid inaccuracy in the assessment of circulating androgen/SHBG levels. 4. Girls with gynecological age less than 3 years. These studied cases were divided into two groups: Group A: 34 cases with fasting G:I ratio ! 7.0 (insulin-resistant group). Group B: 15 cases with fasting G:I ratio $ 7.0 (noneinsulin-resistant group). Statistical Analysis Assuming a confidence level of 95%, with a sample size of 49, calculated confidence interval was 14%. For comparison of various clinical and biochemical parameters, all parameters was tested for normality pre-test (using Kolmogorov-Smirnov), and in cases in which at least one group failed, the non-parametric Mann-Whitney U test, unless otherwise specified, was done. For comparison of incidence of hirsutism, acne, and AN, the chi-square test was used. P ! 0.05 was considered as significant. Results Table 1 shows the prevalence of IR in adolescent PCOS girls, on the basis of fasting G:I ratio. Of the 49 cases, 34 (69.4%) of cases (Group A) were found to be insulin resistant (Group A) and 15 (30.6%) were non-insulin resistant (group B). Table 2 shows the values of the clinical parameters studied and the differences between the two groups of girls. There were no differences in age, BMI and AC. Frequencies of hirsutism (P 5 0.01), acne (P ! 0.01) and AN (P 5 0.0004) showed significant differences. Table 3 shows the values of the biochemical parameters studied, and the differences in these parameters between the two groups. There were no differences in serum testosterone levels, FAI values and fasting sugar values. Significant differences were noted in SHBG levels (P 5 0.04) and fasting insulin levels (P # 0.0001). Discussion This study was done on 49 adolescent Indian girls with PCOS. There are many studies on insulin resistance in adult PCOS women but scant studies have been done on adolescent girls with PCOS in India.
160
Bhattacharya and Ghosh: Insulin Resistance in Girls with PCOS
Table 1. Prevalence of Insulin Resistance in Adolescent PCOS Girls, Calculated on the Basis of Fasting G:I Ratio
Table 3. Biochemical Parameters of the Two Groups
Fasting G:I ratio
Parameters
Group A Mean (SD)
Group B Mean (SD)
Testosterone level (ng/ml) SHBG (nmol/l) FAI Fasting sugar [mg (%)] Fasting insulin (mu/ml)
0.44 21.9 8.5 89.9 22.6
0.53 30.9 7.8 87.4 8.6
Number of Cases
%
34 15
69.4 30.6
! 7.0 $7.0
The implications of insulin resistance in the context of a typical Indian diet rich in carbohydrates remain to be explored. Adolescents are much less concerned about, and probably unaware of, the long-term sequelae of hyperandrogenism, often accompanied by hyperinsulinemia, which are now coming to light and may threaten their general health after age 40.8 A fasting G:I ratio of less than 7.0 was considered to indicate IR in these girls.4 IR can be an intrinsic defect in PCOS women.5,9,10 Biochemical features such as increased androgen and insulin secretion, typical of PCOS, are also often a feature of a normal adolescence. So the biochemical markers for PCOS can be inconsistent in adolescence.8 It is likely that body fat distribution plays an important role in PCOS women and that their IR is connected very tightly with upper body adiposity.11 This study in adolescent girls shows that the BMI and AC were not significantly different between the insulin-resistant and noneinsulin-resistant groups, calculated upon the basis of fasting G:I ratio. These do not accord well with the results of other authors done on adults.10,12 Dunaif 13 reported the presence of intense insulin resistance in adolescents with PCOS regardless of body composition or abdominal obesity. In clinical practice, abdominal circumference is measured as a surrogate measure of visceral fat. Visceral fat, also called central or abdominal fat, is metabolically distinct from subcutaneous fat. It is resistant to the antilipolytic effects of insulin and releases excessive amounts of free fatty acids. These free fatty acids lead to IR in liver and the muscle. In response to it, in the liver, there is increased Table 2. Clinical Parameters of the Two Groups of PCOS Girls Parameters Age (years) BMI (kg/m2) AC (cm) Hirsutism present (FG score 5 O6) Acne present AN present
Group A Mean (SD) Group B Mean (SD) 16.7 (1.8) 26.8 (4.1) 80.2 (9.5) n (%) 15 (44.1)* 21 (61.7)** 20 (58.8)***
*P 5 0.01. **P ! 0.01. ***P 5 0.0004, chi-square test.
17.4 (1.3) 25.8 (4.4) 77.5 (10.0) n (%) 4 (26.6) 12 (80.0) 5 (33.3)
(0.3) (13.3) (6.2) (9.1) (9.5)
(0.3) (14.7)* (7.2) (7.3) (3.1)**
*P 5 0.04, compared to group A. **P 5 0.0001, compared to group A.
gluconeogenesis, and in the muscle there is inhibition of insulin mediated glucose uptake.14e16 Excess fat itself contributes to IR at the level of the adipocyte. When fat cells become too large, they are unable to store additional lipids. Fat is then stored in the muscle, liver, and beta cells of the pancreas, which also contributes to IR in these organs. Visceral fat also produces excess 11-beta-hydroxysteroid dehydrogenase1, an enzyme that converts inactive cortisone to the biochemically active cortisol. This cortisol can promote central adiposity and IR.17 The present study found significant differences in the incidences of hirsutism and AN between insulin resistant and non-insulin resistant girls with PCOS. AN is a clinical parameter which has been found to be independently associated with hyperinsulinemia and, therefore, may be useful as an early indicator of high risk for diabetes.18 This study shows that non-insulin resistant girls had significantly higher incidence of acne compared to insulin resistant girls. But the lower absolute size of this group needs to be taken into account while interpreting this result. Acne is common in adolescence and may not always be due to PCOS. It has been correlated with an increase in dehydroepiandrosterone sulfate (DHEAS) and does not necessarily indicate an abnormal ovulatory mechanism in these adolescent girls.19 The present study did not find any difference in serum total testosterone levels and in FAI values between the two groups. But there were significant differences in SHBG and fasting insulin levels. This shows that neither serum testosterone level nor FAI values can predict or detect IR in adolescent PCOS girls. Luteinizing hormone (LH) and other androgens such as DHEA-sulphate have not been measured in this study. Role of LH and adrenal gland secretion in adolescent PCOS girls need further studies. It has been reported that hyperandrogenism, not necessarily solely due to testosterone, can affect the cellular mechanism of insulin action, stimulating the beta cells of the pancreas to produce more insulin leading to IR.12 The significantly high serum insulin level in insulin-resistant PCOS girls and the state of hyperandrogenism at the cellular level is a matter of great interest.
Bhattacharya and Ghosh: Insulin Resistance in Girls with PCOS
Insulin along with insulin-like growth factor-1 can stimulate the follicular theca to produce ovarian androgens.20 Therefore, this study shows that adolescent PCOS girls who have insulin resistance do not have higher BMI or higher AC, but do have greater incidences of hirsutism and AN, compared to non-insulin resistant adolescent PCOS girls. Thus, two simple clinical parameters, namely hirsutism and AN, will help the clinician to suspect the underlying metabolic abnormalities in adolescent girls with PCOS. Studies have reported a positive correlation between low SHBG and insulin secretion and peripheral glucose utilization.21 The present study finds that the SHBG and insulin levels are significantly different between the two groups. It remains to be determined whether low SHBG levels are indicative of hyperinsulinemia and insulin resistance and this would help define patients at risk for PCOS.22 It is important to note that this study has the limitations of a case series in design and restricted number of clinical/biochemical parameters investigated. Since this is a clinic-based study, fasting G:I ratio was used to detect IR instead of hyperinsulinemic-euglycemic clamp technique. The role of adrenal steroids and desynchronization of LH and FSH secretion from the pituitary gland in the pathogenesis of insulin resistance in adolescent PCOS girls needs more study. Summary and Conclusion Forty-nine adolescent PCOS girls have been studied. Insulin resistance was found in 69.4% of cases by fasting glucose: insulin ratio. There are no differences in BMI, AC, serum testosterone and fasting plasma glucose levels between insulin-resistant and noneinsulin-resistant adolescent girls. There are significant differences in SHBG and fasting insulin levels between the two groups. Insulin resistance in adolescent PCOS girls is associated with significant increase in incidences of hirsutism and acanthosis nigricans. References 1. American Diabetes Association: Consensus Development Conference on Insulin Resistance. Diabetes Care 1998; 21:310 2. DeFronzo RA, Tobin JD, Andres R: Glucose clamp technique: a method for quantifying insulin secretion and resistance. Am J Physiol 1979; 237:E214 3. Legro RS, Finegood D, Dunaif A: A fasting glucose to insulin ratio is a useful measure of insulin sensitivity in women with polycystic ovary syndrome. J Clin Endocrinol Metab 1999; 83:2694 4. Legro RS: Detection of insulin resistance and its treatment in adolescents with polycystic ovary syndrome. J Pediatr Endocrinol Metab 2002; 15(Suppl 5):1367
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