Diet-induced changes in sex hormone binding globulin and free testosterone in women with normal or polycystic ovaries: correlation with serum insulin and insulin-like growth factor-I

Metformin therapy increases insulin-like growth factor binding protein-1 in hyperinsulinemic women with polycystic ovary syndrome

OBJECTIVES

Polycystic ovary syndrome (PCOS) is associated with hyperandrogenism, insulin resistance, compensatory hyperinsulinemia, and increased levels of free insulin-like growth factor-I (IGF-I), presumably due to a decline in IGF binding protein 1 (IGFBP-1). This study was designed to evaluate effects of metformin therapy on serum levels of IGFBP-1 and IGF-I.

STUDY DESIGN

Twenty-seven obese, hyperandrogenic PCOS women with elevated fasting insulin were treated for 12 weeks with metformin (500 mg p.o., t.i.d.). Serum levels of insulin, testosterone, sex hormone binding globulin (SHBG), IGF-I, and IGFBP-1 were measured before and after treatment. Body mass index (BMI) and waist-to-hip ratio (WHR) were assessed at baseline and at the end of therapy.

RESULTS

Metformin therapy significantly increased IGFBP-1 concentration by 38% (P = 0.05) but had no demonstrable effect on the total IGF-I levels. Fasting insulin levels declined by 38% (P = 0.0001) while the glucose/insulin ratio increased by 72% (P = 0.0001) and quantitative insulin sensitivity check index (QUICKI) increased by 8% (P = 0.0001). Metformin treatment also significantly decreased testosterone (by 37%, P = 0.0001) and increased SHBG concentration (by 16%, P = 0.04). Multiple linear regression analysis revealed that baseline IGFBP-1 levels correlated inversely and independently with two baseline parameters: WHR (P = 0.003) and free testosterone index (P = 0.04).

CONCLUSIONS

The present study shows that metformin therapy not only restores normal levels of insulin and testosterone, but also decreases the pool of free-bioactive IGF-I by increasing the levels of circulating IGFBP-1. We provide further arguments in favor of metformin therapy in hyperinsulinemic women with PCOS.

A randomized trial of the effects of two types of short-term hypocaloric diets on weight loss in women with polycystic ovary syndrome

OBJECTIVE

We performed this study as a pilot experiment to investigate the short term effects of two diets of varying composition on weight loss as the primary outcome in obese women with polycystic ovary syndrome (PCOS) seeking fertility.

DESIGN

Randomized clinical trial.

SETTING

Academic medical center.

PATIENT(S)

Thirty-five obese women with PCOS.

INTERVENTION(S)

We examined the effects of a 1-month dietary intervention on the PCOS phenotype. Participants were randomized to one of two energy-restricted diets; high protein (HP: 30% protein, 40% carbohydrate, and 30% fat) or high carbohydrate (HC: 15% protein, 55% carbohydrate, and 30% fat). The fat content was held constant in both diets.

MAIN OUTCOME MEASURE(S)

Primary - change in body weight; Secondary - biometric, hormonal, lipid and lipoprotein, and markers of glucose homeostasis and energy metabolism.

RESULT(S)

Twenty-six women completed the study. Both the HP (-3.7 +/- 1.9 kg) and HC (-4.4 +/- 1.5 kg) diets resulted in significant weight loss, but there was no significant difference in mean weight loss between the two groups. There were also no differences between diets on a variety of measures including circulating androgens, measures of glucose metabolism, and leptin. However, the effects of a hypocaloric diet per se on improving metabolic and reproductive abnormalities in a group of PCOS women were marked by a decline in circulating androgens (P=.03), fasting and area under the curve (AUC) insulins (P<.05) on a 3-hour oral glucose tolerance test (OGTT), and fasting and AUC leptin levels (P<.0001). There was a high prevalence of menstrual bleeding during the trial (14 out of 26 patients).

CONCLUSION(S)

Those who completed the short-term hypocaloric diet had a significant weight loss and a significant improvement in their reproductive and metabolic abnormalities. There was no increased benefit to a high-protein diet. Future diet studies evaluating the ideal composition of a hypocaloric diet in women with PCOS will require a large study population, and will most likely require a multicenter trial.

4: Polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is a common condition characterised by menstrual abnormalities and clinical or biochemical features of hyperandrogenism. Features of PCOS may manifest at any age, ranging from childhood (premature puberty), teenage years (hirsutism, menstrual abnormalities), early adulthood and middle life (infertility, glucose intolerance) to later life (diabetes mellitus and cardiovascular disease). While pelvic ultrasound examination is useful, many women without PCOS have polycystic ovaries; ultrasound evidence is not necessary for the diagnosis. Testing for glucose intolerance and hyperlipidaemia is wise, especially in obese women, as diabetes mellitus is common in PCOS. Lifestyle changes as recommended in diabetes are fundamental for treatment; addition of insulin-sensitising agents (eg, metformin) may be valuable in circumstances such as anovulatory infertility. Infertility can be treated successfully in most women by diet and exercise, clomiphene citrate with or without metformin, ovarian drilling, or ovulation induction with gonadotrophins; in-vitro fertilisation should be avoided unless there are other indications.

Dietary composition in restoring reproductive and metabolic physiology in overweight women with polycystic ovary syndrome

Overweight women with polycystic ovary syndrome (PCOS) were randomized to a high protein (HP; 40% carbohydrate and 30% protein; n = 14) or a low protein (LP; 55% carbohydrate and 15% protein) diet (n = 14). The intervention consisted of 12 wk of energy restriction (approximately 6000 kJ/d), followed by 4 wk of weight maintenance. Pregnancies (two HP and one LP); improvements in menstrual cyclicity, lipid profile, and insulin resistance (as measured by the homeostasis model); and decreases in weight (7.5%) and abdominal fat (12.5%) occurred independently of diet composition. Improvements in menstrual cyclicity were associated with greater decreases in insulin resistance and fasting insulin (P = 0.011). On the LP diet, high density lipoprotein cholesterol decreased 10% during energy restriction (P = 0.008), and the free androgen index increased 44% in weight maintenance stages (P = 0.027). Weight loss leads to improvements in cardiovascular and reproductive parameters potentially mediated by improvements in surrogate measures of insulin resistance. An HP weight loss diet may result in minor differential endocrine and metabolic improvements.

Serum concentrations of sex hormone binding globulin are elevated in kwashiorkor and anorexia nervosa but not in marasmus

BACKGROUND

Customary blood protein markers for malnutrition are of limited value in the diagnosis of protein-energy malnutrition or anorexia nervosa in children and in the follow-up to refeeding in such children.

OBJECTIVES

For these diseases, we compared the diagnostic value of sex hormone binding globulin (SHBG) with that of albumin, transferrin, transthyretin, and retinal binding protein and determined the relations between concentrations of insulin, insulin-like growth factor I, and SHBG.

DESIGN

SHBG was assayed in children with protein-energy malnutrition (29 children with kwashiorkor and 28 with marasmus), in 29 anorectic girls (before and after refeeding), and in age- and sex-matched control subjects.

RESULTS

Mean (+/-SE) serum SHBG concentrations were higher in the children with kwashiorkor (0.18 +/- 0.07 micromol/L) than in the children with marasmus (0.11 +/- 0.05 micromol/L, P < 0.0001) or the control subjects (0.11 +/- 0.03 micromol/L, P < 0.0005). In the children with anorexia nervosa before weight gain, serum SHBG concentrations were significantly higher (0.10 +/- 0.04 micromol/L) than in the age-matched control subjects (0.06 +/- 0.03 micromol/L, P < 0.001) and decreased significantly after 30 d of refeeding (0.04 +/- 0.01 micromol/L, P < 0.0001). This decrease was negatively correlated with insulin-like growth factor I but not with insulin. Mean serum SHBG concentrations were influenced neither by inflammation, as indicated when C-reactive protein was used as a marker (0.27 +/- 0.27, 0.34 +/- 0.42, and <0.04 micromol/L in the children with marasmus, kwashiorkor, and anorexia nervosa, respectively), nor by glomerular filtration, as indicated when cystatin-C was used as a marker (68.46 +/- 23.08, 66.90 +/- 43.08, and 49.23 +/- 7.69 micromol/L, respectively).

CONCLUSIONS

The high SHBG concentration observed in anorexia nervosa and kwashiorkor seems to be of multifactorial origin. For these 2 diseases, SHBG is a reliable marker of nutritional status, is unrelated to either C-reactive protein or cystatin-C, and may be helpful in distinguishing kwashiorkor from marasmus and as a follow-up marker after refeeding.

Metformin does not enhance ovulation induction in clomiphene resistant polycystic ovary syndrome in clinical practice

AIMS

To determine whether metformin pretreatment has beneficial effects in clomiphene resistant infertile women with polycystic ovary syndrome (PCOS) in an infertility clinic.

METHODS

This was a randomized placebo controlled double-blind crossover study of 3 months metformin (1500 mg day-1)/placebo, followed by 3 months metformin/placebo together with clomiphene (50-100 mg for 5 days) for three cycles in clomiphene resistant women with PCOS. The primary outcomes were restoration of spontaneous menses, ovulation induction (spontaneous or clomiphene induced) and pregnancy. Secondary endpoints were changes in biochemical parameters related to androgens and insulin.

RESULTS

Twelve women completed the metformin arm and 14 the placebo arm. Spontaneous menstruation resumed in five metformin treated patients and in six placebo treated women, P=0.63. No women given metformin spontaneously ovulated, although one patient given placebo did, P=0.30. There was no difference in the efficacy of clomiphene between the two groups with ovulation being induced in five (out of 12) metformin treated women and four (out of 14) placebo treated women, P=0.63. Pregnancy occurred in three (out of 12) women given metformin and two (out of 14) women given placebo, P=0.59.

CONCLUSIONS

Metformin is not always beneficial when given to clomiphene resistant infertile women with PCOS in clinical practice.

Revisitando o Hirsutismo

O hirsutismo é definido como o crescimento excessivo de pêlos terminais na mulher, em áreas anatômicas características de distribuição masculina. Pode manifestar-se como queixa isolada, ou como parte de um quadro clínico mais florido, acompanhado de outros sinais de hiperandrogenismo, distúrbios menstruais e/ou infertilidade ou ainda alterações metabólicas relacionadas com hiperinsulinemia/resistência insulínica. O hirsutismo decorre da ação dos androgênios sobre a pele e depende de vários fatores correlacionados: níveis de androgênios e da SHBG e conseqüente relação hormônio livre/hormônio ligado, grau de sensibilidade cutânea aos androgênios, capacidade de conversão de androgênios em estrogênios e outras interconversões entre esteróides. Pode ser classificado em duas categorias: a) associado a uma hiperprodução glandular de androgênios pelos ovários e/ou suprarrenais ou b) decorrente de uma hiperutilização isolada dos androgênios circulantes pelo folículo pilo-sebáceo, correspondendo ao hirsutismo dito "idiopático". A causa mais freqüente do hirsutismo de origem glandular é a síndrome dos ovários policísticos. A hiperplasia adrenal congênita forma não clássica (HAC-NC) por deficiência da 21-hidroxilase é a causa mais freqüente de hirsutismo de origem adrenal, embora sua prevalência, entre mulheres hirsutas como um todo, seja relativamente baixa. Outras causas menos freqüentes são a síndrome de Cushing e os tumores virilizantes, ovarianos ou adrenais. Neste artigo são enfocados criticamente aspectos da avaliação diagnóstica do hirsutismo e os principios do tratamento com base em sua etiologia. São abordadas as indicações e limitações do uso de diferentes antiandrogênios e outros fármacos relacionados.

Polycystic ovary syndrome in adolescence and early adulthood

Polycystic ovaries and the associated syndrome are recognized as the most common cause of endocrine disturbances in adult women, but much less research has been performed to examine how polycystic ovary syndrome (PCOS) presents in girls and young women. Polycystic ovaries have been demonstrated in childhood, and there is evidence to show that even very young women may show symptoms and signs of the associated syndrome. Closer examination of younger populations (less-than-or-eq, slant 25 years of age), and in particular, studies of girls during the transition from puberty into early adulthood (adolescence), may provide new insights into the pathogenesis and natural history of polycystic ovaries and PCOS, and may indicate whether polycystic ovaries could potentially be considered as a marker for health screening. Consideration should be given to the management of girls and young women with polycystic ovaries and PCOS as this group may have different needs and health risks compared with older women.

Hyperinsulinaemia and polycystic ovary syndrome

Over the past 20 years, it has been established that hyperinsulinaemia is a fundamental disturbance in many women with polycystic ovary syndrome (PCOS). A subgroup of women with this syndrome have 'metabolic PCOS' which can be considered to be a pre-diabetic state. Clinically, this subgroup is most easily identified in obese women with a strong family history of diabetes in whom menstrual disturbance is the predominant feature. There is an urgent need to define the more subtle features in young lean women with PCOS, in whom the metabolic syndrome is yet to emerge, which would enable the prediction of future health risks. The molecular mechanisms of insulin resistance leading to hyperinsulinaemia are now being elucidated. Abnormalities of both insulin secretion and intracellular insulin signalling have both been proposed in women with PCOS. Strategies to lower serum insulin concentrations include diet, exercise and possibly, oral insulin sensitizing agents such as metformin. Although the short-term efficacy of reducing hyperinsulinaemia in women with PCOS is clear, the best method to prevent the progression to diabetes later in life has not been defined.

Changes in sex hormone-binding globulin, insulin, and serum lipids in postmenopausal women on a low-fat, high-fiber diet combined with exercise

Dietary factors including fat and fiber have been reported to play a role in the development of breast cancer, possibly mediated by changes in estradiol. Diet and exercise have been shown to affect levels of sex hormone-binding globulin (SHBG), which in turn regulate the bioavailability of estradiol. Diet and exercise also affect insulin levels, which play a role in the synthesis of SHBG, and the hormone itself is a potent mitogen for many cancer cell lines. This study was designed to measure the effects of a low-fat, high-fiber diet, combined with regular aerobic exercise, on the levels of SHBG, insulin, and serum lipids in postmenopausal women with or without hormone replacement therapy (HRT). Two groups of postmenopausal women, 11 on HRT and 11 not on HRT, underwent a low-fat (1O% fat calories), high-fiber (65-70 g/day) diet-and-exercise intervention for three weeks. Serum SHBG, insulin, and lipids were measured before and after the regimen. After the intervention, SHBG levels were significantly increased for the women on HRT (44.5 +/- 3.4 vs. 62 +/- 6.4 nmol/l) and the women not on HRT (32.1 +/- 4.6 vs. 45.5 +/- 6.1 nmol/l, both changes p < 0.01). Also after the intervention, insulin levels were significantly reduced for the women on HRT (196 +/- 44.4 vs. 119.8 +/- 28.7 pmol/l) and the women not on HRT (144.2 +/- 17.9 vs. 115.5 +/- 20.8 pmol/l, both changes p < 0.01). Body mass index and total cholesterol were significantly reduced for both groups of women (all changes p < 0.01). Although the exact mechanism for the change in SHBG is not known, the increases in SHBG and reductions in insulin as a result of this lifestyle intervention should reduce the risk for breast cancer in postmenopausal women.

Polycystic ovary syndrome. A diagnostic challenge

Polycystic ovary syndrome remains a diagnostic challenge because there is no single defining test. The clinical presentation must dictate the extent of the work-up. The typical PCOS patient has a history of irregular menses and appears hirsute. Demonstration of ovulatory dysfunction and hyperandrogenism can also be made by appropriate hormonal measurements. An ultrasound showing multiple small ovarian follicles can support a diagnosis of PCOS in the patient for whom the clinical diagnosis has been made. Other causes of hyperandrogenism and ovulatory dysfunction should be excluded.

Energy balance and cancer: the role of insulin and insulin-like growth factor-I

Recent theories propose that a Western lifestyle may increase cancer risk through alterations in the metabolism of insulin and insulin-like growth factors (IGF: McKeown-Eyssen, 1994; Giovannucci, 1995; Kaaks, 19%; Werner & LeRoith, 1996). Insulin regulates energy metabolism, and increases the bioactivity of IGF-I, by enhancing its synthesis. and by decreasing several of its binding proteins (IGFBP; IGFBP-1 and -2). Insulin and IGF-I both stimulate anabolic processes as a function of available energy and elementary substrates (e.g. amino acids). The anabolic signals by insulin or IGF-I can promote tumour development by inhibiting apoptosis, and by stimulating cell proliferation. Furthermore, both insulin and IGF-I stimulate the synthesis of sex steroids, and inhibit the synthesis of sex hormone-binding globulin (SFIBG), a binding protein that regulates the bioavailability of circulating sex steroids to tissues. The present paper reviews epidemiological findings relating the risk of cancers of the colo-rectum, pancreas, breast, endometrium and prostate to body size (obesity, height) and physical activity, and discusses the relationships between obesity and physical activity and plasma levels of insulin, IGF-I and IGFBP. Subsequent sections review epidemiological findings relating cancer risk to indices of chronic hyperinsulinaemia, and to plasma levels of IGF-I and IGFBP. Conclusions are that chronic hyperinsulinaemia may be a cause of cancers of the colon, pancreas and endometrium, and also possibly of the breast. On the other hand, elevated plasma IGF-I, as total concentrations or relative to levels of IGFBP-3, appears to be related to an increased risk of prostate cancer, breast cancer in young women, and possibly cob-rectal cancer. For cancers of the endometrium, breast and prostate, these findings are discussed in the context of relationships between insulin and IGF-I and levels of bioavailable sex steroids.

The decrease in luteinizing hormone secretion in response to weight reduction is inversely related to the severity of insulin resistance in overweight women

Controversial effects of weight reduction on gonadotropin secretion in obesity have been reported. As a result of pulsatility, single serum samples or frequent sampling studies are somewhat limited with regard to monitoring LH and FSH concentrations. We studied follicular phase nocturnal urinary (nu) LH and FSH secretion and glucose metabolism (150-min euglycemic hyperinsulinemic clamp) during 1 menstrual cycle/30-day period before and after weight reduction in 10 severely overweight infertility patients (age, 29 +/- 3.1 yr; body mass index, 37.1 +/- 3.3 kg/m2; +/-SEM). A 6-week very low calorie diet was followed by a 4-week normocaloric period. The urinary LH and FSH results reported represent samples taken 12 to 2 days before the LH surge, or 10 consecutive samples in the case of amenorrhea. We observed a decrease of 8% (P < 0.001) in percent body fat mass and a 5% (P < 0.005) reduction in waist to hip ratio. Mean nu-LH decreased by 45% [6.06 +/- 1.05 (+/-SEM) to 3.22 +/- 0.71 IU/L], whereas mean nu-FSH remained unchanged. Insulin-stimulated glucose uptake increased by 41% (P < 0.01), which was accounted for by a significant increase in nonoxidative glucose disposal (P = 0.003). Serum sex hormone-binding globulin concentrations increased by 39% (P < 0.01), and insulin-like growth factor (IGF)-binding protein-1 (IGFBP-1) levels increased by 46% (P < 0.05). Fasting serum insulin concentrations decreased by 38%, those of leptin by 37%, those of androstenedione by 32%, those of testosterone by 20% (all P < 0.01), and those of dehydroepiandrosterone sulfate by 13% (P < 0.05). The percent change in nu-LH correlated negatively with glucose uptake (r = -0.76; P < 0.01) and the increase in serum sex hormone-binding globulin (r = -0.85; P < 0.005) and positively with the percent change in waist to hip ratio (r = 0.79; P < 0.01). The absolute nu-LH levels after weight reduction correlated significantly with fasting insulin concentrations (r = 0.88; P < 0.001) and negatively with glucose uptake (r = -0.67; P < 0.05). No significant relationships were found between absolute levels or changes in nu-LH concentrations and leptin, IGF-I, IGFBP-3, or IGFBP-1 concentrations. Our findings suggest that weight reduction with a very low calorie diet results in a decrease in nu-LH concentrations, a reduction in the LH/FSH ratio, and FSH predominance favoring folliculogenesis. The decrease in LH concentrations is inversely related to the severity of insulin resistance. It is possible that the decrease in LH secretion with weight reduction is more dependent on the absolute levels of insulin sensitivity than on the degree of general adiposity.

Insulin resistance, polycystic ovary syndrome and metformin

Polycystic ovary syndrome (PCOS) is the most common disorder of ovarian function in premenopausal women. PCOS is characterised by chronic anovulation and androgen excess with clinical manifestation of irregular menstrual cycles, hirsutism and/or acne. Insulin resistance with resultant hyperinsulinaemia, irrespective of excess weight or frank obesity, has been reported in patients with PCOS, and, as insulin has a direct effect on ovarian androgen production in vitro, insulin resistance may play a crucial role in the physiopathology of PCOS. Although the molecular mechanism(s) of insulin resistance in PCOS is unclear, excessive insulin-independent serine phosphorylation of the beta subunit of the insulin receptor, as reported in some patients with PCOS, has been put forward as a new mechanism for insulin resistance. Insulin-sensitising agents have recently been investigated for their role in the short term treatment of insulin resistance in PCOS. Controlled studies have shown that metformin administration, by promoting bodyweight loss, can decrease fasting and stimulated plasma insulin levels. However, other studies have shown metformin 500 mg 3 times daily to decrease insulin secretion and to reduce ovarian production of 17alpha-hydroxyprogesterone with recovery of spontaneous or clomifene-induced ovulation, independently of weight loss. These findings suggest a new indication for metformin and present insulin-sensitising agents as a novel approach in the treatment of ovarian hyperandrogenism and abnormal ovulation in PCOS. They also suggest that long term administration of metformin might be helpful in treating insulin resistance, thus reducing risks of type 2 (non-insulin-dependent) diabetes and cardiovascular disease in these patients.

Restoration of reproductive potential by lifestyle modification in obese polycystic ovary syndrome: role of insulin sensitivity and luteinizing hormone

Weight reduction and exercise have been shown to help with menstrual disturbance and infertility in obese women with polycystic ovary syndrome. We studied the relationship between insulin sensitivity and ovulation patterns in 18 infertile anovulatory obese polycystic ovary syndrome (PCOS) women (NO) with normal glucose tolerance, aged between 22-39 yr with a body mass index of 27-45 kg/m2, before and after a 6-month diet and exercise program. This program promotes healthy lifestyle factors, but does not lead to rapid weight loss. The anthropometric, metabolic, and endocrine factors of these subjects were compared to those of 10 age- and weight-matched PCOS women with regular monthly ovulation (RO). Before lifestyle modification, the anovulatory subjects had greater central obesity than regular ovulators, as assessed by percent central fat (NO, 45.7 +/- 0.8%; RO, 42.2 +/- 1.6%; P < 0.05), higher glucose increment after glucose challenge (NO, 10.1 +/- 1.0 mmol/L; RO, 6.4 +/- 1.1 mmol/L; P < 0.02), lower insulin sensitivity index (NO, 1.2 +/- 0.2; RO, 2.8 +/- 0.6 micromol/kg x min/pmol/L; P < 0.005), higher plasma LH (NO, 8.9 +/- 0.9; RO, 4.6 +/- 0.9 IU/L; P < 0.005), and lower plasma sex hormone-binding globulin (NO, 18.0 +/- 2.5; RO, 27.8 +/- 5.7 nmol/L; P < 0.05]. Anovulatory subjects were classified as responders (R) to the intervention if they regained ovulation during the study. As a result of intervention, R showed an 11% reduction in central fat, a 71% improvement in insulin sensitivity index, a 33% fall in fasting insulin levels, and a 39% reduction in LH levels. None of these parameters changed significantly in nonresponders (NR). At the end of the study, R had lower fasting insulin (R, 13.6 +/- 1.7; NR, 23.0 +/- 3.5 mU/L) and LH levels (R, 5.0 +/- 1.7; NR, 7.4 +/- 1.4 IU/L), but similar androgen levels compared to NR. We conclude that lifestyle modification without rapid weight loss leads to a reduction of central fat and improved insulin sensitivity, which restores ovulation in overweight infertile women with PCOS. Lifestyle modification is the best initial management for obese women seeking to improve their reproductive function.

Hyperinsulinism and sex hormones in young adult African Americans

Hyperinsulinemia is a risk factor for cardiovascular disease, and is linked with non-insulin-dependent diabetes mellitus (NIDDM), hyperlipidemia, obesity, and hypertension. Sex hormones also play a role in the metabolic alterations associated with the risk for cardiovascular disease. A reduction in sex hormone-binding globulin (SHBG) may be predictive of future NIDDM particularly in women. The postmenopausal decline in estrogen is also associated with an increase in risk factor expression in women. Since African Americans experience a greater prevalence of NIDDM, obesity, and hypertension, conditions associated with hyperinsulinemia, the purpose of this study was to determine if alterations in sex hormone levels are associated with the plasma insulin concentration in young adult African Americans, and to determine if there are sex differences in the effect of insulin on lipids and sex hormones. In a sample of 221 nondiabetic African American men (n = 105) and women (n = 116) with a mean age of 31 years, we examined the relationship of the plasma insulin concentration with the body mass index (BMI), blood pressure, plasma lipids, and sex hormones, including free testosterone, estradiol, and SHBG. Plasma insulin increased with the BMI and other measures of adiposity (P<.001) in men and women. Significant correlations of insulin with plasma lipids were also present in both sexes. There was a significant inverse correlation of insulin with SHBG in both men (r = .28, P = .007) and women (r = .27, P = .02). There was a significant direct correlation of insulin with free testosterone in women (r = .032, P<.001). Stepwise multiple regression analyses with insulin as the dependent variable detected the BMI, triglyceride, and apolipoprotein A1 as significant contributors to the plasma insulin concentration in men. In women, the multiple regression model detected percent body fat, low-density lipoprotein (LDL) cholesterol, and free testosterone as significant contributors to plasma insulin. These data on young African Americans demonstrate a significant relationship between hyperinsulinemia and obesity, atherogenic lipid status, and lower SHBG. In the premenopausal women, the lower SHBG is linked with higher free testosterone, favoring a condition of relative androgen excess.

Endocrine methods of ovulation induction

The rationale of ovulation induction is to achieve the development of a single follicle and ultimately a singleton healthy baby. Problems faced by women with anovulatory polycystic ovary syndrome are the sensitivity of the ovary to stimulation and health issues such as obesity. This chapter will discuss medical management including strategies to lose weight, address hyperinsulinaemia with insulin-sensitizing agents, such as metformin, and outline methods of ovulation induction from the usual first-line therapy of clomiphene citrate and the subsequent use of gonadotrophin therapy in clomiphene-resistant patients. Appropriately directed surgical ovulation induction with laparoscopic ovarian diathermy appears to be as efficacious as gonadotrophin therapy but will not be discussed in the context of this chapter.

Polycystic ovary syndrome: current and future treatment paradigms

Polycystic ovary syndrome is characterized by excess levels of circulating androgens and by chronic anovulation. Although the fundamental pathophysiologic defect has not been determined, women with polycystic ovary syndrome are known to be uniquely insulin resistant. Obesity in polycystic ovary syndrome aggravates the underlying predisposition towards insulin resistance. Diagnostic criteria that focus on menstrual irregularity are more likely to discriminate insulin-resistant women than are such criteria as abnormal gonadotropin secretion or ovarian morphologic characteristics. About 40% of patients with polycystic ovary syndrome demonstrate glucose intolerance (either impaired glucose tolerance or type 2 diabetes) in response to an oral glucose challenge. The lack of a clear causal mechanism in the syndrome has led to a multitude of symptom-oriented treatments, with few therapies improving all aspects of the endocrine abnormalities associated with polycystic ovary syndrome. Many of these therapies-such as ovulation induction with medical agents-hold increased risks for women with polycystic ovary syndrome, including ovarian hyperstimulation syndrome and multiple gestation. Empirical studies of interventions that improve insulin sensitivity in polycystic ovary syndrome (either weight loss and diet programs or pharmaceutical agents) have been shown to improve the endocrine abnormalities in the syndrome. Initial results with antidiabetic agents (specifically insulin-sensitizing agents) are promising but need to be confirmed with larger, randomized studies.

Understanding the underlying metabolic abnormalities of polycystic ovary syndrome and their implications

Women with polycystic ovary syndrome have an increased rate of obesity, with a propensity toward abdominal deposition of body fat. Independent of obesity, at least half of affected women have insulin resistance. To understand the mechanisms of insulin resistance in polycystic ovary syndrome, it is necessary to understand normal insulin signaling. Women with polycystic ovary syndrome have normal binding of insulin to its receptor but have decreased activation of events downstream of the receptor. This insulin resistance occurs mostly in the peripheral tissues (muscle and fat cells), and results in increased pancreatic insulin secretion to maintain normal glucose levels. Obese women with polycystic ovary syndrome have a relative defect in insulin secretion. At least 20% of obese patients with polycystic ovary syndrome have glucose intolerance or diabetes, versus about 5% of the healthy age-matched population. Obesity and insulin resistance probably increase the risk of cardiovascular disease in women with polycystic ovary syndrome. The metabolic features of polycystic ovary syndrome are important health risk factors and need to be considered seriously, even if the patient seeks treatment for other concerns.

Polycystic ovary syndrome: a new direction in treatment

Polycystic ovary syndrome is a diagnosis made in 5%-10% of women between late adolescence and the menopause. Patients may present with oligomenorrhoea or amenorrhoea, anovulation or infertility, hirsutism or acne. Women with the syndrome have at least seven times the risk of myocardial infarction and ischaemic heart disease of other women, and by the age of 40 years up to 40% will have type 2 diabetes or impaired glucose tolerance. Polycystic ovary syndrome is associated with insulin resistance, with consequent hyperinsulinaemia and (frequently) hyperlipidaemia and obesity. Recent research has shown that the application of diabetes management techniques aimed at reducing insulin resistance and hyperinsulinaemia (such as weight reduction and the administration of oral hypoglycaemic agents) can not only reverse testosterone and luteinising hormone abnormalities and infertility, but can also improve glucose, insulin and lipid profiles. The management of polycystic ovary syndrome should now include patient education and attention to diabetes and cardiovascular risk factors such as hyperlipidaemia, obesity, physical exercise, glucose intolerance, hypertension and cigarette smoking.

Insulin resistance in polycystic ovary syndrome: treating a phenotype without a genotype

PCOS women are uniquely insulin resistant. The underlying genetic defect in insulin action is unknown. Obesity aggravates the underlying predisposition to insulin resistance. Diagnostic criteria which focus on menstrual irregularity are more likely to identify insulin resistant women. About 40% of PCOS women display glucose intolerance (either impaired glucose tolerance or type 2 diabetes) in response to an oral glucose challenge. The lack of a clear etiologic mechanism to the syndrome has led to a multitude of symptom-oriented treatments with few therapies improving all aspects of the endocrine syndrome of PCOS. Empirical studies of interventions improving insulin sensitivity in PCOS, either weight loss/diet programs or pharmaceutical agents, have been shown to improve the endocrine abnormalities in the syndrome. These initial results with anti-diabetic agents, though promising, need to be confirmed in larger, randomized studies.

Growth hormone and ovarian function

Growth and reproductive development are closely co-ordinated during puberty but there is also evidence that growth hormone (GH) may have a physiological role in adult ovarian function. Both GH and the insulin-like growth factors (IGFs) have been shown to augment granulosa cell proliferation and steroidogenesis in the human Graafian follicle, suggesting that GH may act as a 'co-gonadotrophin' at ovarian level. Furthermore, the intra-ovarian 'IGF system' (i.e. IGFs and IGF-binding proteins) may be implicated in folicular atresia and in disorders of follicular function associated with polycystic ovary syndrome (PCOS). The clinical importance of GH to ovarian function in the adult is illustrated by the finding that adjuvant GH treatment reduces the dose of exogenous gonadotrophin which is required to induce folliculogenesis in women with hypogonadotrophic hypogonadism. There is, however, no evidence that GH supplementation is of significant clinical benefit in the management of patients with other ovulatory disorders--including PCOS--or in superovulation protocols for in vitro fertilization.

Human chorionic gonadotropin stimulation to assess for ovarian hyperandrogenism

STUDY OBJECTIVE

To determine whether human chorionic gonadotropin (hCG) stimulation elicits an exaggerated 17-hydroxyprogesterone (17-OHP) response in patients with functional ovarian hyperandrogenism.

METHODS

In this clinical study, healthy volunteers and hyperandrogenic patients in an outpatient General Clinical Research Center (GCRC) setting were studied. Five adolescent girls with functional ovarian hyperandrogenism were studied. Six healthy women with regular menstrual cycles volunteered for this study. Steroid hormone responses to hCG stimulation were measured before and 30, 240, and 300 minutes after hCG injection. Congenital adrenal hyperplasia was excluded through ACTH stimulation testing and molecular genetic analysis.

MAIN OUTCOME MEASURE

17-OHP responses.

RESULTS

Mean basal 17-OHP concentrations were greater in the hyperandrogenic patients, 110.4+/-41.2 ng/dL versus 61.8+/-28.6 ng/dL. After hCG stimulation, 17-hydroxyprogesterone concentrations significantly increased in the patients and were unchanged in the healthy controls.

CONCLUSION

hCG stimulation elicited greater 17-hydroxyprogesterone responses in adolescent girls with functional ovarian hyperandrogenism compared with healthy controls. hCG stimulation may be helpful to confirm ovarian hyperandrogenism.

Treatment of androgen excess in females: yesterday, today and tomorrow

Hirsutism, acne and androgenic alopecia represent, in females, some of the manifestations of the clinical spectrum of hyperandrogenism. These pictures represent not only cosmetic damage, but also a source of remarkable psychological distress. Often hirsutism is regarded as presumptive evidence of a lack of femininity. The major diagnostic concern is to exclude an ovarian or adrenal androgen-secreting tumor, a congenital hyperplasia or polycystic ovary disease. Ethnic background should be taken into account together with the progression of the symptoms. Following the etiology, surgery and exogenous glucocorticoids or inhibition of gonadotropin secretion have to be carefully chosen in the management of different kinds of hyperandrogenism. Several pharmacologic agents have recently shown the ability to block the androgen receptors at target organ sites, thus allowing a specific antiandrogenic treatment. In some cases cosmetic measures could be of great value. Obesity accompanied by hyperinsulinemia can represent the main cause of ovary androgen hypersecretion; therefore a reduced body weight and muscle activity represent the basis of any treatment. Some other drugs, such as long-acting analogs of somatostatin, could be considered among possible drugs for the future. The aim of this article is to provide an appraisal of what is presently known about the regulation of hair growth, the various causes of excessive androgen secretion and the current methods to solve, safely, this important feminine clinical problem.

Up-regulation of IGF binding protein-1 as an anticarcinogenic strategy: relevance to caloric restriction, exercise, and insulin sensitivity

The mitotic rate of stem cells is a major determinant of cancer risk. Insulin-like growth factors (IGFs) are virtually obligate stimulants of cell turnover in nearly every tissue. IGF activity is subject to rapid modulation by hepatic release of IGF binding protein-1 (IGFBP-1), a factor whose synthesis is suppressed by insulin and increased by glucagon. Up-regulation of IGFBP-1 production can be expected to decrease IGF activity and thereby diminish cancer risk. Measures that sensitize peripheral tissues to insulin, and thereby down-regulate insulin secretion, can be expected to increase IGFBP-1 synthesis, provided that they do not unduly sensitize hepatocytes as well. Prolonged aerobic exercise and caloric restriction also increase IGFBP-1 production. Since IGF-1 suppresses hepatic synthesis of sex hormone binding globulin (SHBG), down-regulation of IGF activity will increase SHBG levels and thus diminish the availability of free sex hormones--an effect that should further decrease cancer risk in sex hormone-responsive tissues. These considerations rationalize many findings in animal and epidemiologic studies, and suggest that non-diabetic insulin resistance may be a significant cancer risk factor. Increased IGF activity associated with insulin resistance may also promote benign hyperplasias-most notably atherosclerosis. Hyperinsulinemia stimulates intimal hyperplasia indirectly, via IGF.

The relationship between insulin sensitivity and insulin-like growth factor-binding protein-1

Insulin has been shown to regulate insulin-like growth factor-binding protein-1 (IGFBP-1) in vivo and in vitro. Insulin resistance is a feature of the polycystic ovary syndrome (PCOS). We have studied the relationship between insulin sensitivity (S1) and the circulating concentration of IGFBP-1 in a group of young women and in some who had PCOS. A case-control study has been carried out comparing reproductively normal women with women with PCOS (defined as women with oligo- or amenorrhea associated with androgen excess). Fifteen women with clinical PCOS and ten age- and weight-matched controls were studied. S1 was measured by the frequently sampled intravenous glucose tolerance test (FSIGT) using the minimal model technique. IGFBP-1, insulin-like growth factor-I (IGF-I) and growth hormone levels were measured before and during the FSIGT. Circulating testosterone, dehydroepiandrosterone (DHEA) and its sulfate (DHEAS) levels were measured while the subjects were fasting. S1 and IGFBP-1 levels were significantly lower in the PCOS group than in controls (S1/10(-5) min-1/pM] mean +/- SE 3.8 +/- 0.8 vs. 8.5 +/- 1.3, p < 0.03; IGFBP-1 [ng/ml] mean +/- SE 26.6 +/- 4.2 vs. 56.0 +/- 5.9, p < 0.005). In women with PCOS, IGFBP-1 concentrations related negatively to the body mass index (BMI) (r = -0.77, p < 0.003) and positively to S1 (r = 0.76, p < 0.003). S1 remained a significant predictor of IGFBP-1 concentrations when controlled for BMI (combined r2 = 0.35, p < 0.05). No relationship was found between androgen levels and IGFBP-1. Insulin sensitivity contributed to the difference in IGFBP-1 levels found in women with PCOS. Whether the reduced concentrations of IGFBP-1 play a role in the pathophysiology of PCOS is uncertain, but it may act to alter delivery of IGF to peripheral tissues in insulin-resistant individuals.

Nutrition, hormones, and breast cancer: is insulin the missing link?

Breast cancer incidence rates are high in societies with a Western lifestyle characterized by low levels of physical activity, and by an energy-dense diet rich in total and saturated fat and refined carbohydrates. Epidemiologic studies, so far mostly on postmenopausal women, have shown that breast cancer risk is increased in hyperandrogenic women, with decreased levels of plasma sex-hormone binding globulin, and with increased levels of testosterone and of free estrogens. This paper describes the role of hyperinsulinemia as a physiologic link between nutritional lifestyle factors, obesity, and the development of a hyperandrogenic endocrine profile, and reviews evidence that may or may not support the theory that chronic hyperinsulinemia is an underlying cause of breast cancer. An hypothesis is presented, stipulating that breast cancer risk is increased not only in hyperandrogenic postmenopausal women, but also in premenopausal women with mild hyperandrogenism and normal (ovulatory) menstrual cycles. The author suggests further investigation as to whether there is a positive association between risk of breast cancer before menopause and subclinical forms of the polycystic ovary syndrome (PCOS), and to what extent diet and physical activity during childhood, by modulating the degree of insulin resistance during adolescence, may or may not be determinants of a PCO-like hyperandrogenic endocrine profile persisting into adulthood.

Decreases in ovarian cytochrome P450c17 alpha activity and serum free testosterone after reduction of insulin secretion in polycystic ovary syndrome

BACKGROUND

Insulin resistance and increased ovarian cytochrome P450c17 alpha activity are both features of the polycystic ovary syndrome. P450c17 alpha, which is involved in androgen biosynthesis, has both 17 alpha-hydroxylase and 17,20-lyase activities. Increased activity of this enzyme results in exaggerated conversion of progesterone to 17 alpha-hydroxyprogesterone in response to stimulation by gonadotrophin. We hypothesized that hyperinsulinemia stimulates ovarian P450c17 alpha activity.

METHODS

We measured fasting serum steroid concentrations and the response of serum 17 alpha-hydroxyprogesterone to leuprolide, a gonadotrophin-releasing hormone agonist, and performed oral glucose-tolerance tests before and after oral administration of either metformin (500 mg three times daily) or placebo for four to eight weeks in 24 obese women with the polycystic ovary syndrome.

RESULTS

In the 11 women given metformin, the mean (+/- SE) area under the serum insulin curve after oral glucose administration decreased from 9303 +/- 1603 to 4982 +/- 911 microU per milliliter per minute (56 +/- 10 to 30 +/- 6 nmol per liter per minute) (P = 0.004). This decrease was associated with a reduction in the basal serum 17 alpha-hydroxyprogesterone concentration from 135 +/- 21 to 66 +/- 7 ng per deciliter (4.1 +/- 0.6 to 2.0 +/- 0.2 nmol per liter) (P = 0.01) and a reduction in the leuprolide-stimulated peak serum 17 alpha-hydroxyprogesterone concentration from 455 +/- 54 to 281 +/- 52 ng per deciliter (13.7 +/- 1.6 to 8.5 +/- 1.6 nmol per liter) (P = 0.01). The serum 17 alpha-hydroxyprogesterone values increased slightly in the placebo group. In the metformin group, the basal serum luteinizing hormone concentration decreased from 8.5 +/- 2.2 to 2.8 +/- 0.5 mlU per milliliter (P = 0.01), the serum free testosterone concentration decreased from 0.34 +/- 0.07 to 0.19 +/- 0.05 ng per deciliter (12 +/- 3 to 7 +/- 2 pmol per liter) (P = 0.009), and the serum sex hormone-binding globulin concentration increased from 0.8 +/- 0.2 to 2.3 +/- 0.6 microgram per deciliter (29 +/- 7 to 80 +/- 21 nmol per liter) (P < 0.001). None of these values changed significantly in the placebo group.

CONCLUSIONS

In obese women with the polycystic ovary syndrome, decreasing serum insulin concentrations with metformin reduces ovarian cytochrome P450c17 alpha activity and ameliorates hyperandrogenism.

The entero-insular axis in polycystic ovarian syndrome

We investigated the contributions made by the entero-insular axis, proinsulin and the fractional hepatic extraction of insulin to the hyperinsulinaemia characteristic of polycystic ovarian syndrome (PCOS). We measured plasma glucose, gastric inhibitory polypeptide (GIP), glucagon-like peptide-1 (7-36 amide) (GLP-1(7-36) amide), immunoreactive insulin (IRI), intact proinsulin (IPI), and C-peptide concentrations during a 75 g oral glucose tolerance test in seven normal weight women with PCOS and eight healthy women. Women with PCOS had higher fasting (P = 0.05) and integrated (P < 0.01) IRI concentrations than controls. Fasting C-peptide levels were similar in both groups but integrated C-peptide (P < 0.05) concentrations were greater in PCOS subjects than controls. Fasting and integrated concentrations of glucose, GIP and GLP-1(7-36) amide were similar in subjects with PCOS and controls. Although fasting IPI concentrations were similar in both groups, integrated IPI concentrations were higher (P = 0.05) in patients with PCOS. Women with PCOS had similar fasting but higher (P < 0.05) integrated IRI:C-peptide molar ratios than controls. Fasting and integrated IPI:IRI molar ratios were similar in both groups. These results confirm that lean women with PCOS have peripheral hyperinsulinaemia. The mild fasting hyperinsulinaemia is due to increased pancreatic secretion, whereas the stimulated hyperinsulinaemia is due to both pancreatic hypersecretion and reduced fractional hepatic extraction of insulin. Hyperproinsulinaemia is modest and appropriate in PCOS, GIP and GLP-1(7-36) amide do not contribute to the stimulated hyperinsulinaemia in PCOS.

Disturbances in insulin secretion and sensitivity in women with the polycystic ovary syndrome

Insulin resistance, defined as a diminished effect of a given dose of insulin on glucose homeostasis, is a highly prevalent feature of women with PCOS. Insulin resistance in PCOS is closely associated with an increase in truncal-abdominal fat mass, elevated free fatty acid levels, increased androgens, particularly free testosterone through reduced SHBG levels, and anovulation. The causes for insulin resistance in PCOS are still unknown. One line of evidence suggests that an increase in truncal-abdominal fat mass and subsequently increased free fatty acid levels induce insulin resistance in women with PCOS. Increased effects of corticosteroids and a relative reduction in oestrogen and progesterone seem to be involved in the aberrant body fat distribution. Conversely, there are also results supporting primary, genetic target cell defects as a cause of insulin resistance in PCOS. An explanation for these seemingly contradictory results could be that the group of women with PCOS is heterogeneous with respect to the primary event in carbohydrate/insulin disturbances. Also insulin secretion in PCOS is characterized by heterogeneity. At one end of the spectrum is a large subgroup of mainly obese women with reduced insulin secretion, which appears to result from failure of the beta cells to compensate for insulin resistance in susceptible women, resulting in glucose intolerance and NIDDM. In the insulin-resistant patients with normal glucose tolerance, most of the hyperinsulinaemia is probably due to secondarily increased insulin secretion and decreased insulin degradation. However, a component of the increased first-phase insulin release is not due to measurable insulin resistance. Notably, this is also found in lean women with normal insulin sensitivity, and is not reversed after weight reduction, in contrast to the findings for insulin resistance. The implications of this enhanced insulin release are not fully clear, but it may tentatively be associated with carbohydrate craving and subsequently increased risks for development of obesity and insulin resistance. It may represent a primary disturbance of insulin secretion in PCOS or may be associated with the perturbed steroid balance in anovulation. The insulin-androgen connection in PCOS appears to be amplified by several different mechanisms, notably in both directions, the initiating event probably varying between individuals. Thus insulin increases the biological availability of potent steroids, primarily testosterone, through the suppression of SHBG synthesis. Insulin is also involved as a progonadotrophin in ovarian steroidogenesis, with the possible net result of interfering with ovulation and/or increasing ovarian androgen production in states of hyperinsulinaemia. Conversely, testosterone may indirectly contribute to insulin resistance through facilitating free fatty acid release from abdominal fat, but perhaps also through direct muscular effects at higher serum levels. It seems likely that this constitution, presumably genetic, would provide evolutionary advantages in times of limited nutrition, given the energy-saving effects of insulin resistance. Hypothetically, hyperinsulinaemia (primary) could provide a stimulus to ensure intake of nourishment, but unlimited food supplies could in some cases initiate a vicious 'anabolic' circle, in which several of the proposed amplifying mechanisms between insulin and androgens--in both directions--could take part.

Polycystic ovary syndrome: clinical aspects

The clinical presentation of PCOS is likely to be the end process of many pathogenic mechanisms, the definition of which is only now beginning to be unravelled. While the application of ultrasonography to the diagnosis of PCOS has undoubtedly added greatly to our understanding of the breadth of the disorder and our appreciation of its heterogeneity, careful distinction has to be made between polycystic ovaries and polycystic ovary syndrome in order to define optimal treatments, particularly in women with menstrual disturbance. In the presence of obesity, no treatment regimen can neglect weight reduction as the main thrust of intervention, no matter whether the goal be to improve hirsutism or infertility.

Regulation of sex hormone-binding globulin production by isoflavonoids and patterns of isoflavonoid conjugation in HepG2 cell cultures

The effect of the isoflavonoid phytoestrogens daidzein, equol, and genistein on sex hormone-binding globulin (SHBG) levels, SHBG mRNA transcript levels, and SHBG gene methylation was studied in HepG2 cell cultures by fluoroimmunometric SHBG assay and Northern and Southern hybridizations, respectively. The effect of 17 beta-estradiol on these parameters was studied as a control. The metabolism of isoflavonoids in HepG2 cells was determined by isotope dilution gas chromatography-mass spectrometry, after ion-exchange chromatography. Daidzein and equol increased SHBG levels in parallel intracellularly and extracellularly, whereas genistein increased SHBG levels only within the cells, resembling thus the effect of 17 beta-estradiol. The difference may originate from the fact that genistein has more hydroxyl groups than daidzein and equol. The regulation of SHBG production by phytoestrogens appears to occur at the post-transcriptional level. Firstly, daidzein, equol, or genistein did not have a clear effect on the steady-state SHBG mRNA levels. Secondly, no effect on SHBG gene methylation was observed by genistein. The findings applied also to 17 beta-estradiol. However, as the SHBG gene was more methylated in SHBG-negative MCF-7 cells than in SHBG-positive HepG2 cells, DNA methylation may play a role in the tissue-specific activation of this gene. The metabolism of isoflavonoids in HepG2 cells yielded mainly unconjugated and sulfated compounds. Similar metabolism in hepatocytes in vivo might retain their biological activity in tissues responsive to estrogens.

Effects of abstinence on sex hormone profile in alcoholic patients without liver failure

Excessive ethanol ingestion induces hypoandrogenism in male subjects. To confirm its presence and to study its relationship with the degree of liver damage and alcohol abstinence, plasma sex hormones were measured in alcoholic patients without liver failure, after two different abstinence periods. Patients were 30 male chronic alcoholics admitted to the Alcoholism Ward for treatment of their addiction. On admission, we measured: testosterone (T), estradiol (E), follicle stimulating hormone (FSH), luteinizing hormone (LH) and sex-hormone binding globulin (SHBG). A liver biopsy was also performed. These measurements were repeated at discharge and were also done in 15 normal volunteers. On admission (mean abstinence 1.9 +/- 1.7 days) total T was similar to controls, FSH was lower (p < 0.02) and high levels of SHBG were found (3.5 fold increase, as compared to controls). Histologically, 9 patients had normal liver; 14 had moderate alterations and 7 showed marked alterations. Hormonal values were not different in these 3 groups. At discharge, 11.1 +/- 4.7 days after admission, T, E and FSH did not show significant changes but LH decreased (8.2 +/- 5.2 mIU/ml vs 12.9 +/- 4.1, p < 0.001); SHBG also decreased (65.4 +/- 21.6 nmol/l vs 117.2 +/- 33.3, p < 0.001) to values that still were twice those of controls. It is concluded that alcoholic patients without clinical signs of liver failure have normal plasma testosterone levels, irrespective of their histologic liver alterations and high plasma SHBG levels that decreased significantly after a short abstinence. The concomitant LH decrease suggests that hypoandrogenism is likely in these patients. Fast changes in SHBG levels rise the possibility that this protein is candidate marker of alcoholism.

Diurnal variation of sex hormone binding globulin and insulin-like growth factor binding protein-1 in women with polycystic ovary syndrome

OBJECTIVES

The aim of this study was to examine (1) the diurnal variation in SHBG and (2) the inter-relationships of insulin, IGF-I, SHBG and IGFBP-1 over 24 hours in 10 women with anovulatory PCOS and compare them with weight-matched ovulatory controls.

PATIENTS AND METHODS

The two groups comprised 10 anovulatory women with PCOS (as defined by clinical, ultrasound and biochemical criteria) and 10 weight matched controls. Serum samples were taken at two-hourly intervals for 24 hours and stored for measurement of SHBG, IGFBP-1, insulin and IGF-I. Differences between the groups were compared using the Wilcoxon ranked paired tests of the individual peak and trough concentrations in each group. The variation in insulin, IGFBP-1 and SHBG concentrations over 24 hours was tested using two-way analysis of variance with the factors time and subject. Spearman's correlation coefficient was calculated from the subjects' median value over 24 hours.

RESULTS

The median (interquartile range) body mass index (BMI) was 25.2 (22.2-29.3) in the PCOS group and 24.3 (23.2-25.7) kg/m2 in the control group. Serum testosterone (T) and LH levels were significantly raised in the PCOS group compared to the control group; T 3.8 (2.9-5.6) vs 1.9 (1.9-2.5) nmol/l (P < 0.007) and LH 12 (10-15) vs 4.1 (3.6-4.5) IU/I (P < 0.005) respectively. There was no diurnal variation in SHBG. The median (interquartile ranges) of the peak SHBG concentrations was lower in the PCOS group: 29.4 (14.9-39.4) vs 52.1 (39.4-61) nmol/l in the control group (P < 0.01). The fasting levels of insulin at 0600 h (median (interquartile ranges)) were not significantly different between the groups; 6.6 (5.4-9.8) and 6.2 (1.9-7.6) mU/l, respectively, although the peak median concentrations were significantly different; PCOS 66.1 (50.9-129.2) vs 40 (36.1-74.2) mU/l (P < 0.05). Two-way analysis of variance showed a diurnal variation in insulin concentrations in the control group (P = 0.001) but not in the PCOS group (P = 0.1). The diurnal variation in IGFBP-1 was similar in the two groups but the peak median levels were lower in the women with PCOS 54.9 (22.3-79.2) vs 71.5 (60.5-99.3) micrograms/l (P < 0.03). The decline in IGFBP-1 concentrations correlated with the increase in insulin concentrations. The IGF-I concentrations were similar in the two groups. There was a significant negative correlation between SHBG and insulin (P < 0.05) and between insulin and IGFBP-1 (P < 0.01).

CONCLUSION

This study demonstrates that there is no diurnal variation in SHBG concentrations and confirms the finding of a marked diurnal variation in the concentration of IGFBP-1. Women with PCOS who are anovulatory have an abnormal pattern of insulin secretion with an absence of diurnal variation compared to weight matched controls. This provides further evidence of the relative insulin resistance which is independent of weight found in women with anovulatory PCOS. The inverse correlations of insulin concentrations with SHBG and IGFBP-1 support the role of insulin as a possible regulator of the circulating levels of these binding proteins although the difference in the time course of their response makes it unlikely that they are co-regulated.

Sex hormone-binding globulin and female reproductive function

Although sex steroids have long been known to influence serum concentrations of SHBG, it is now recognized that nutritional factors may be more important in the regulation of SHBG in women. Thus, SHBG concentrations are negatively correlated with body mass index (BMI) and, more particularly, to indices of central adiposity. Polycystic ovary syndrome (PCOS), the most common cause of anovulatory infertility, is associated with truncal obesity, hyperandrogenism and hyperinsulinaemia. There is evidence that insulin may be the humoral mediator of the weight-dependent changes in SHBG. Serum SHBG concentrations are inversely correlated with both fasting and glucose-stimulated insulin levels, and insulin has been shown to have a direct inhibitory effect on SHBG synthesis and secretion by hepatocytes in culture. However, the interrelationship of BMI, insulin and SHBG appears to be different in women with PCOS from that in normal subjects. The clinical importance of the weight-related suppression of SHBG is illustrated by the finding of a greater prevalence of hirsutism in obese women PCOS compared with their lean counterparts. Obese subjects with PCOS have similar total testosterone concentrations to lean PCO women but have lower SHBG and reciprocally higher free testosterone levels. Calorie restriction results in reduction of serum insulin followed by an increase in SHBG and a fall in free testosterone but an isocaloric, low-fat diet has no significant effect on SHBG concentrations. Weight reduction in obese, hyperandrogenaemic women with PCO is an important approach to the management of both anovulation and hirsutism.

Insulin-like growth factors: clinical experience in ovarian function

Insulin, insulin-like growth factor, and insulin-like growth factor binding proteins have been shown to play major roles in the modulation of both normal and disturbed ovarian physiology. Identification of many of the actions of these peptides was initially characterized using animal models. However, an increasing body of evidence has emerged to clarify their contributions in human reproductive function. It is clear that at various stages of folliculogenesis, local steroid production acts in concert with intraovarian peptides to promote dominant follicle development. This review will discuss the physiologic role(s) of the insulin-insulin-like growth factor-insulin-like growth factor binding protein family in reproductive function and disorders of androgen excess.

Relations between sex hormones, sex hormone binding globulin, insulin-like growth factor-I and insulin-like growth factor binding protein-1 in post-menopausal breast cancer patients

OBJECTIVE

Oestrogens, androgens and anti-endocrine drugs such as tamoxifen and aminoglutethimide influence plasma insulin-like growth factor-I (IGF-I). IGF-I, in turn, has been found to stimulate the peripheral aromatase in vitro. The aim of this study was to examine relations between sex hormones, IGF-I and insulin-like growth factor binding protein-1 (IGFBP-1) in post-menopausal women with breast cancer.

DESIGN

To measure plasma sex steroids, sex hormone binding globulin (SHBG), IGF-I, IGFBP-1, insulin and urinary oestrogen metabolites in post-menopausal women with breast cancer not receiving any endocrine therapy.

PATIENTS

Thirty-two patients had fasting blood samples obtained between 0800 and 1000 h. A sub-group of 10 patients had 24-hour urine oestrogen metabolites determined.

MEASUREMENTS

Plasma steroids and proteins were measured by radioimmunoassays. Urinary oestrogens were measured by GC-MS.

RESULTS

SHBG correlated negatively with plasma androstenedione (P < 0.001), insulin (P < 0.001), IGF-I, height and plasma oestrone sulphate (P < 0.025 for all), but positively with plasma IGFBP-1 (P < 0.025). IGFBP-1 correlated negatively with IGF-I (P < 0.001) and the testosterone/SHBG ratio (P < 0.05). Neither IGF-I nor IGFBP-1 correlated with any of the plasma or urinary sex hormones or with the oestrone/androstenedione and oestradiol/testosterone ratios. Multivariate analysis revealed plasma SHBG to correlate positively with IGFBP-1 (P = 0.029) and negatively with insulin (P = 0.031). Plasma IGFBP-1 correlated negatively with IGF-I (P < 0.0001) but not with insulin.

CONCLUSION

Our results do not suggest any influence of plasma sex steroids in physiological concentrations on IGF-I or IGFBP-1 in post-menopausal breast cancer patients, nor do they indicate IGF-I at physiological concentrations influences the ratios between plasma oestrogens and their androgen precursors.

The response of the growth hormone and insulin-like growth factor I axis to medical castration in women with polycystic ovarian syndrome

OBJECTIVE

To assess the impact of ovarian hormone deprivation on serum concentrations of GH and insulin-like growth factor I (IGF-I) in women with polycystic ovarian syndrome (PCOS).

DESIGN

Growth hormone and IGF-I levels were measured before, during, and at the end of a 6-month period of treatment with leuprolide acetate (LA) depot. Normal cycling and ovariectomized women served as controls.

SETTING

The Clinical Research Center of Northwestern University Medical School.

PATIENTS

Six women with PCOS, seven normal cycling women, and six ovariectomized women.

INTERVENTIONS

The PCOS and normal cycling subjects were treated with six consecutive monthly injections of LA depot 3.75 mg IM.

MAIN OUTCOME MEASURES

Circulating concentrations of GH and IGF-I.

RESULTS

After 3 months of treatment, GH levels decreased modestly in the PCOS group; however, these changes were not significant. No further decline was observed at 6 months. Growth hormone levels were unaffected in the normal cycling group. Levels of IGF-I remained unchanged in both groups. Mean baseline levels of both GH and IGF-I in the ovariectomized group were lower than those of the normal cycling and PCOS groups at all time points, but not significantly so.

CONCLUSIONS

Medical castration fails to significantly alter serum GH and IGF-I levels in either normal cycling or women with PCOS. These data indicate that GH secretion is not modulated by hormones of ovarian origin in either group, at least over the period of time studied.

Comparative effects of GH, IGF-I and insulin on serum sex hormone binding globulin

OBJECTIVE

The serum level of sex hormone binding globulin (SHBG) changes inversely with that of both insulin and insulin-like growth factor (IGF-I), during several nutritional conditions, as well as in response to GH treatment. However, with exogenous IGF-I administration, endogenous IGF-I increases, while insulin decreases. In order to study the separate roles of these hormones in controlling SHBG metabolism, we compared SHBG levels in patients treated with IGF-I and GH.

DESIGN AND PATIENTS

Serum levels of IGF-I, insulin and SHBG were measured before and during the treatment of patients with IGF-I or GH. Blood samples were drawn in the fasting state, prior to and during therapy, 24 hours after drug administration. Sixteen children and adults with Laron syndrome (LS) received daily s.c. injections of IGF-I (120-150 micrograms/kg) for up to 5 months. Three adults with isolated GH deficiency (IGHD) received daily s.c. injections of GH (0.03-0.06 U/kg) for 16 months. Two groups of nine prepubertal children with constitutional short stature (CSS) received GH (0.1 U/kg/day) for 3 months.

MEASUREMENTS

Serum levels of insulin and acid extractable IGF-I were determined by RIA, and that of SHBG by IRMA.

RESULTS

Basal insulin and SHBG levels were within normal range in the LS, IGHD and CSS patients. IGF-I levels were low in LS and IGHD patients, and normal in the CSS children. The mean peak response to chronic therapy was as follows: in LS patients, IGF-I administration decreased insulin levels to 62%, and increased SHBG levels by 64% above basal values. Chronic GH therapy in IGHD caused a marked rise in both IGF-I levels (473%), and insulin levels (96%), and a gradual decline of SHBG to 75% of the basal concentration. In GH treated CSS patients, serum IGF-I peaked at 80% and insulin levels at 102% above the respective basal levels, while SHBG decreased to 83% after 5 days of treatment.

CONCLUSION

The results obtained in Laron syndrome, isolated GH deficiency and constitutional short stature patients treated with IGF-I or GH, indicate that serum insulin had consistently an inverse relation with the levels of circulating SHBG. No relation was found between IGF-I and SHBG levels.

Acute cholinergic blockade with low dose pirenzepine reduces the insulin and glucose responses to a mixed meal in obese women with the polycystic ovary syndrome

OBJECTIVES

Pirenzepine, a selective muscarinic cholinergic antagonist, reduces plasma insulin and plasma glucose responses to a mixed meal in a dose dependent fashion in normals and in patients with non-insulin dependent diabetes. We have studied the effects of pirenzepine on plasma insulin, plasma glucose, growth hormone (GH), androstenedione, testosterone, insulin-like growth factor-I (IGF-I) and IGF binding protein 1 (IGFBP-1) responses to a mixed meal in obese clinically hyperandrogenic women with the polycystic ovary syndrome.

SUBJECTS AND METHODS

Six obese women with polycystic ovary syndrome (BMI range 27.3-39.8 kg/m2) were studied in random sequence, and received either placebo or pirenzepine (single doses of 50, 100, or 200 mg) one hour before a standard test meal. Blood was sampled every 15 minutes for 2 hours after the meal and every 30 minutes thereafter for a total of 4 hours.

RESULTS

Mean fasting plasma insulin concentrations were increased. Peak post-prandial plasma insulin concentrations were reduced significantly by all three doses used. Post-prandial integrated plasma insulin concentrations were reduced by the two higher doses. Peak post-prandial plasma glucose concentrations were also reduced. The late post-prandial GH surge was significantly suppressed by all three doses. However, plasma androstenedione, testosterone, IGF-I and IGFBP-1 concentrations were not significantly different when placebo was compared with pirenzepine 200 mg.

CONCLUSIONS

Acute cholinergic muscarinic blockade with pirenzepine significantly reduces meal stimulated plasma insulin and plasma glucose concentrations in clinically hyperandrogenic women with polycystic ovary syndrome. The ability of pirenzepine to reduce plasma insulin without worsening glycaemia is a particular advantage and may be therapeutically relevant. Further studies are under way to assess the usefulness of pirenzepine in long-term suppression of plasma insulin in this group of patients.

Clinical implications of hyperinsulinaemia in women

In the polycystic ovary syndrome, hyperinsulinaemia is commonly found in women with hirsutism, oligomenorrhoea and acanthosis nigricans and this subset of patients possess adverse risk factors for coronary artery disease, particularly reduced HDL2 concentrations. Conversely, raised serum insulin concentrations are not common in women with PCOS in whom raised serum LH concentrations or regular menstrual cycles are present. We postulate that both direct ovarian and indirect actions of insulin (through changes in IGFI-I, IGFBP-I and SHBG concentrations) play important roles in determining androgen concentrations in women. Many intriguing questions follow from this link between the control of nutrition and reproduction and many old observations required re-examination in this new light. Vital to our understanding in this field will be the cause of moderate hyperinsulinaemia, the action of insulin on the normal ovary, and the importance of adverse surrogate risk factors for heart disease in hyperinsulinaemic women.

Response of sex hormone binding globulin and insulin-like growth factor binding protein-1 to an oral glucose tolerance test in obese women with polycystic ovary syndrome before and after calorie restriction

OBJECTIVE

We determined the relationship of short-term changes in circulating insulin concentrations, resulting from an oral glucose load, to those in both sex hormone binding globulin (SHBG) and insulin-like growth factor binding protein 1 (IGFBP-1) and assessed the effect of a short-term low calorie diet on the levels of SHBG and IGFBP-1 during an oral glucose tolerance test.

DESIGN

A within-group comparison of biochemical indices during an oral glucose tolerance test before and after calorie restriction.

PATIENTS AND METHODS

Six obese women with polycystic ovary syndrome with mean (SD) BMI 34.2 (3.4) kg/m2 were studied before and after one month on a very low calorie diet (350 kcal/day; Cambridge diet). Each subject was given a 75-g oral glucose load after an overnight fast and blood samples were taken every 30 minutes for 3 hours. These were analysed for glucose, insulin, SHBG, and IGFBP-1.

RESULTS

All the women lost weight (range 1.7-9.5 kg). The SHBG concentrations did not change significantly during the oral glucose tolerance test but there was a highly significant decline in IGFBP-1 levels both before (0 min, mean (SD) 27.3 (10.6); 180 min, 8.9 (4.2) micrograms/l) and after (0 min, 28.4 (12.1); 180 min, 6.2 (2.1) micrograms/l, P < 0.001) dieting. The sum of the SHBG concentrations during the test, however, was significantly lower prior (129.9 (40.5) nmol/l) to calorie restriction than after (164.3 (70.6) nmol/l), whereas there was no significant effect of dieting on the IGFBP-1 response to glucose.

CONCLUSIONS

The changes in insulin and SHBG concentrations found after dieting have been confirmed. SHBG levels, in contrast to IGFBP-1, do not change in response to a short-term increase in insulin or glucose concentrations. The difference in the response of the two binding proteins may be explained by differences in their half-lives in the circulation or the regulation of mRNA for the peptides by insulin. This study confirms that insulin regulates both SHBG and IGFBP-1 but that there is a difference in the time course of the response of the two proteins to insulin.

Thyroxine treatment increases circulating levels of insulin-like growth factor binding protein-1: a placebo-controlled study

OBJECTIVE

Thyroid hormones affect carbohydrate metabolism in the liver, and hepatic insulin-like growth factor binding protein-1 (IGFBP-1) participates in glucose counter-regulation, so we studied the effects of oral thyroxine on serum IGFBP-1.

DESIGN

The study was performed on a placebo-controlled cross-over basis covering 3 months' thyroxine and 3 months' placebo administration.

PATIENTS

Eight patients taking anticonvulsant medication and four patients with hypothalamic hypothyroidism were given thyroxine, 150-200 micrograms daily for 3 months, or placebo.

MEASUREMENTS

Serum IGFBP-1, sex hormone binding globulin, free T3 and free T4, TSH and IGF-I levels were measured after an overnight fast before treatment, and at the end of each 3-month period.

RESULTS

Anticonvulsant medication had no significant effect on serum IGFBP-1. After 3 months' thyroxine treatment the serum IGFBP-1 levels (69; 58-167 micrograms/l; median and interquartile range, respectively) were significantly higher than those after placebo treatment (44; 23-58 micrograms/l; P = 0.002), or the pretreatment levels (54; 19-81 micrograms/l, P = 0.005). The IGFBP-1 levels rose in all 12 patients after thyroxine treatment, the median rise being 2.1-fold compared to placebo levels. No change was found in serum IGF-I concentrations.

CONCLUSIONS

Oral thyroxine produces a rise in serum IGFBP-1 levels without a change in serum IGF-I concentration.

The role of free fatty acids in regulating the tissue availability and synthesis of sex steroids

Sex steroids and dietary fat intake have been implicated in the growth of breast tumours. We have previously shown that the plasma free oestradiol fraction is increased in women with breast cancer and that the addition of free fatty acids (FFA) to plasma can increase the free oestradiol fraction in vitro. In the present study we have examined the distribution of oestradiol and testosterone in serum obtained from European women (EW) and Asian (Gujarati) women (GW) living in north-west London. Fat intake by these women is similar but GW, who are vegetarians, consume a greater proportion of unsaturated fats. In serum from perimenopausal GW, the free testosterone concentration was significantly higher than for EW (11.1 +/- 3.6 pmol/l vs 8.7 +/- 3.4 pmol/l, p < 0.05). Although a significant correlation was found between the free testosterone and FFA concentrations for GW (r = 0.49, p < 0.05), concentrations of sex-hormone binding globulin (SHBG) were significantly lower in GW than EW. The finding of lower SHBG concentration in GW was confirmed in a second study in postmenopausal women (EW, 60.1 +/- 34.1 nmol/l; GW, 37.8 +/- 20.5 nmol/l, p < 0.05). However, no difference in the free oestradiol fraction or concentration was detected for EW and GW and no correlations with total or individual FFA were found. It is concluded from this study that while dietary fats may have an important role in the development of breast tumours, it is unlikely to be mediated by FFA inhibiting the binding of sex steroids to plasma proteins.