Hyperandrogenism, insulin resistance, and acanthosis nigricans syndrome: a common endocrinopathy with distinct pathophysiologic features

In vivo regulation of the steroidogenic activity of rat luteal cells by insulin

The aim of the present study was to determine the long-term effects of insulin treatment on luteal cell function. For this purpose, superovulated prepubertal rats were treated with insulin (group I) or vehicle (group C) for 9 days. Serum progesterone (P4) levels were increased in the insulin-treated group (55 +/- 10 vs 134 +/- 31 ng/ml, P < 0.05). Isolated luteal cells were incubated 3 h, and P4 and 20 alpha-hydroxy-progesterone (20 alpha-OH-P) were measured in the incubation media. A decrease in P4 levels and an increase in 20 alpha-OH-P values [P4 (ng/ml): C = 26.6 +/- 0.3; I = 20 +/- 2; 20 alpha-OH-P (ng/ml): C = 62 +/- 2; I: 120 +/- 7; P < 0.01] were observed in group I. In addition, progestagen (P4 + 20 alpha-OH-P) levels were higher in group I (C = 88 +/- 2; I = 140 +/- 9 ng/ml; P < 0.001). When cytochrome P450scc contents were measured by immunoblotting, a marked increase was observed in luteal cells obtained from group I. LH receptor numbers were decreased in luteal cells isolated from group I (C = 388,834 +/- 14,146; I = 303,057 +/- 13,392 sites/cell; P < 0.001) with a concomitantly diminished LH responsiveness. It is concluded that in vivo treatment of superovulated rats with insulin increases luteal progestagen production by increasing the content of cytochrome P450scc.

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.

Endogenous sex hormones: impact on lipids, lipoproteins, and insulin

Estrogen use has been reported to decrease triglyceride and low-density lipoprotein cholesterol (LDL-C) and increase high-density lipoprotein cholesterol (HDL-C). Estrogen use increases the secretion of large, very low-density lipoprotein cholesterol (VLDL-C) and also stimulates the uptake of VLDL-C by the liver and increases the catabolism of LDL-C in the liver. Sex hormones may affect several enzymes involved in the metabolism of HDL-C and triglyceride and may also affect lipolysis. In both pre- and postmenopausal women, several studies have shown that increased glucose and insulin concentrations are associated with increased free testosterone and decreased sex hormone binding globulin. The temporal direction of this relationship in premenopausal women is not clear, however. In contrast to women, increased androgen concentrations in men do not seem to be associated with increased cardiovascular risk factors, although testosterone concentrations are associated with increased HDL-C and decreased insulin concentrations. Dehydroepiandrosterone (DHEA) and dehydroepiandrosterone sulfate (DHEAS) appear to be associated with improved cardiovascular risk factors in men, but this connection in women is less clear.

Estrogen resistance caused by a mutation in the estrogen-receptor gene in a man

BACKGROUND AND METHODS

Mutations in the estrogen-receptor gene have been thought to be lethal. A 28-year-old man whose estrogen resistance was caused by a disruptive mutation in the estrogen-receptor gene underwent studies of pituitary-gonadal function and bone density and received transdermal estrogen for six months. Estrogen-receptor DNA, extracted from lymphocytes, was evaluated by analysis of single-strand-conformation polymorphisms and by direct sequencing.

RESULTS

The patient was tall (204 cm [80.3 in.]) and had incomplete epiphyseal closure, with a history of continued linear growth into adulthood despite otherwise normal pubertal development. He was normally masculinized and had bilateral axillary acanthosis nigricans. Serum estradiol and estrone concentrations were elevated, and serum testosterone concentrations were normal. Serum follicle-stimulating hormone and luteinizing hormone concentrations were increased. Glucose tolerance was impaired, and hyperinsulinemia was present. The bone mineral density of the lumbar spine was 0.745 g per square centimeter, 3.1 SD below the mean for age-matched normal women; there was biochemical evidence of increased bone turnover. The patient had no detectable response to estrogen administration, despite a 10-fold increase in the serum free estradiol concentration. Conformation analysis of his estrogen-receptor gene revealed a variant banding pattern in exon 2. Direct sequencing of exon 2 revealed a cytosine-to-thymine transition at codon 157 of both alleles, resulting in a premature stop codon. The patient's parents were heterozygous carriers of this mutation, and pedigree analysis revealed consanguinity.

CONCLUSIONS

Disruption of the estrogen receptor in humans need not be lethal. Estrogen is important for bone maturation and mineralization in men as well as women.

Body fat distribution has weight-independent effects on clinical, hormonal, and metabolic features of women with polycystic ovary syndrome

This study was performed to investigate whether different patterns of body fat distribution may have distinct effects on the clinical, hormonal, and metabolic features of women with clinical hyperandrogenism such as polycystic ovary syndrome (PCOS). Ninety-seven consecutive women with PCOS were included in the study after assessment of gynecological and obesity history and careful clinical examination. Women were divided into three tertile groups based on the waist to hip ratio (WHR). Those with peripheral body fat distribution (P-BFD) had a WHR of less than 0.80, those with intermediate body fat distribution (I-BFD) had a WHR of 0.81 to 0.90, and those with abdominal body fat distribution (A-BFD) had a WHR exceeding 0.90. Baseline blood and urine samples were obtained for several hormone and lipid determinations, and the response of glucose, insulin, and C-peptide to a glucose oral challenge (75 g) was investigated. In the PCOS group, WHR values were higher than those used to define P-BFD and A-BFD in the normal female population. As WHR values increased, a significantly greater prevalence of obesity and acanthosis nigricans and a lower prevalence of acne was present. No significant differences were present in any of the other clinical features between the three groups. Ovarian morphology and volumes were similar in all groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Case report: defective beta and alpha cell regulation in patients with hyperinsulinemia and acanthosis nigricans

Beta cell hypersecretion is associated with the syndrome of hyperandrogenism, insulin resistance, and acanthosis nigricans. It is unknown whether concomitant alpha cell secretory dysfunction occurs in patients with this syndrome. The authors evaluated the gastroenteropancreatic hormones in four family members with varying degrees of the hyperandrogenism, insulin resistance, and acanthosis nigricans syndrome. Gastroenteropancreatic hormones were measured during oral glucose tolerance test with and without subcutaneous octreotide injection. The study revealed that the administration of subcutaneous octreotide resulted in suppression of beta cell function (insulin and c-peptide) but had no effect or a delayed effect on alpha cell secretion (glucagon). Furthermore, the severity of glucagon abnormalities paralleled that of beta cell hypersecretion and the clinical and phenotypic manifestations of acanthosis nigricans in our four patients. We speculate that this alpha cell aberration could potentially be involved in the altered glucose homeostasis and perhaps the skin manifestations of this syndrome. Therefore, glucagon levels should be evaluated in the hormonal studies in patients with hyperandrogenism, insulin resistance, and acanthosis nigricans syndrome.

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.

Insulin resistance improves in hyperandrogenic women treated with Lupron

OBJECTIVE

To examine if changes in insulin sensitivity and glucose effectiveness in women with polycystic ovarian disease (PCOD) occurred after ovarian androgen suppression with a GnRH agonist, leuprolide acetate (LA, Lupron; TAP Pharmaceuticals, Deerfield, IL) using the minimal model method.

DESIGN

Twelve patients with PCOD were tested in the untreated state (baseline) and after 6 weeks of LA treatment. Subjects were divided into two groups based on the degree of impairment of their baseline insulin sensitivity index (SI; (min-1) (microU/mL-1): mild insulin resistance (SI > 1) or severe insulin resistance (SI < 1).

RESULTS

In all patients, serum T was significantly decreased from elevated baseline levels to normal female concentrations after 6 weeks of LA therapy. Insulin sensitivity in PCOD patients with mild insulin resistance significantly improved from baseline after 6 weeks of LA therapy, whereas no change in SI on LA therapy was seen in PCOD women with severe insulin resistance. Glucose utilization independent of increased insulin secretion did not change as a function of LA treatment in either group.

CONCLUSION

These findings indicate a significant improvement in SI in mildly insulin-resistant women with PCOD after suppression of ovarian function with LA treatment.

Bone mineral density in hyperandrogenic amenorrhoea

The authors assessed bone mineral density in androgenized amenorrheic (group A; n = 9) and androgenized nonamenorrheic patients (group B; n = 30) and compared it with controls (n = 22). Bone mineral density of group A patients (1.023 +/- 0.045 g/cm2) did not differ from controls (1.047 +/- 0.83 g/cm2); both groups had significantly lower values than group B women (1.099 +/- 0.085 g/cm2). Of the hormonal variables explaining bone mineral density in androgenized women, only dehydroepiandrosterone sulfate had a significant negative correlation (r = -0.45). In contrast to other forms of amenorrhea, women with hyperandrogenic amenorrhea seem to be spared from osteopenia.

Ultrasound diagnosis of polycystic ovaries

Ultrasound characterization of ovarian morphology has become an important aspect of gynecological endocrinology. The classic ultrasound features of polycystic ovaries are an increased number of small follicles together with abundant stroma. The exact criteria vary according to the ultrasound technique used. The method, however, has been validated both laparoscopically and histologically. Using laparoscopic inspection as a reference test, ultrasonography was calculated to have a sensitivity of 91% and a specificity of 100%. As a group, anovulatory women with PCO have the classic endocrine features of polycystic ovarian syndrome, but in a proportion of cases the finding of PCO at scan appears to be irrelevant to the presenting disorder. Ultrasound diagnosis of PCO is also limited by its inability to display either ovary in about 16% of women.

The thrifty genotype and non-insulin dependent diabetes

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Mutations in the insulin receptor gene in patients with genetic syndromes of insulin resistance and acanthosis nigricans

Mutations of the insulin receptor gene have been identified in patients with genetic syndromes of insulin resistance associated with acanthosis nigricans. These mutations impair insulin responses by reducing the number of insulin receptors on the surface of target cells, or by reducing the receptor's ability to bind insulin or to undergo insulin-stimulated autophosphorylation, an important step in insulin action. Studies of mutant receptors expressed in transfection systems have contributed to our understanding of the structure-function relationships of the insulin receptor.

Human ovarian 17-ketosteroid oxidoreductase: unique characteristics of the granulosa-luteal cell and stromal enzyme

OBJECTIVES

We attempted to test the hypothesis that distinct forms of the 17-ketosteroid oxidoreductase exist in the human ovary and to compare its activity in stroma obtained from normally cycling women and from hyperandrogenic women.

STUDY DESIGN

Human ovarian granulosa-luteal cell and stromal 17-ketosteroid oxidoreductase were examined in cell incubations and subcellular homogenates.

RESULTS

In subcellular homogenates of granulosa-luteal cells 17-ketosteroid oxidoreductase activity was greater in the cytosol fraction than in the membrane fraction. In contrast, in homogenates of both ovarian stroma and Leydig cells its activity was greater in the membrane fraction than in the cytosol fraction. At the substrate concentrations used estrone was a better substrate than androstenedione for the granulosa-luteal cell 17-ketosteroid oxidoreductase. In contrast, androstenedione was a better substrate than estrone for that in ovarian stromal and Leydig cell membranes. In incubations of ovarian stroma from hyperandrogenic women, significantly more testosterone accumulated in the medium per milligram of tissue than in the medium of incubations of ovarian stroma from normally cycling women (142 +/- 48 vs 7.9 +/- 7.5 pg testosterone per milligram of tissue per 48 hours, mean +/- SD, p less than 0.05). The ratio of testosterone to androstenedione was significantly higher in the medium of incubations of ovarian stroma from hyperandrogenic women than in that from normally cycling women (0.61 vs 0.25, mean, p less than 0.05). The ratio of serum testosterone to androstenedione was significantly greater in hyperandrogenic women than in normally cycling control women (0.31 +/- 0.11 vs 0.20 +/- 0.03, mean +/- SD, p less than 0.05).

CONCLUSION

The localization (cytosol fraction) and substrate specificity (estrone) of the granulosa-luteal cell 17-ketosteroid oxidoreductase enzyme resembles that seen in human placenta. The localization (membrane fraction) and substrate specificity (androstenedione) of the ovarian stromal 17-ketosteroid oxidoreductase enzyme resembles that seen in Leydig cells. It may be one enzyme that exists in multiple forms or it may be two (or more) enzymes. In some hyperandrogenic women the ovarian stromal 17-ketosteroid oxidoreductase may be more active than in normally cycling women, contributing to an abnormally increased testosterone production rate.

Relationship of sex hormone-binding globulin to lipid, lipoprotein, glucose, and insulin concentrations in postmenopausal women

Sex hormones play a major role in determining the risk of cardiovascular disease. While several studies have shown that reduced sex hormone-binding globulin (SHBG) is associated with increased insulin and triglyceride and decreased high-density lipoprotein cholesterol (HDLC) in premenopausal women, little data are available for postmenopausal women. We hypothesized that in postmenopausal women decreased SHBG would be associated with an atherogenic pattern of cardiovascular risk factors. We measured SHBG, lipids, lipoproteins, glucose, and insulin concentrations, and systolic and diastolic blood pressure in 101 postmenopausal women. SHBG was negatively associated with triglyceride (r = -.21) and insulin (r = -.47) concentrations and positively associated with HDLC concentrations (r = .47). After adjustment for overall adiposity (body mass index) and upper body adiposity (as measured by the ratio of waist to hip circumferences), SHBG was still associated with HDLC and insulin, but not with triglyceride. Sex hormones were not related to systolic and diastolic blood pressure. The results may help to explain an association of increased androgenicity, as measured by a lower SHBG concentration, with diabetes and risk of cardiovascular disease in older women.

Decreased hepatic insulin extraction in upper body obesity: relationship to unbound androgens and sex hormone binding globulin

Hyperinsulinemia is a well-recognized entity of simple obesity. It is demonstrated that hyperinsulinemia is associated with upper body fat and fat cell hypertrophy. Androgen excess and lower levels of sex hormone binding globulin (SHBG) may produce fat cell hypertrophy and hyperinsulinemia as well. We measured serum insulin and C-peptide levels during an OGTT in two groups of obese premenopausal women to determine whether the hyperinsulinemia is due to hypersecretion or due to a diminished hepatic extraction of insulin. In this study, we found no correlation between the insulin and C-peptide levels or their ratio and the degree of obesity. However, a significant correlation was found between the waist-to-hip circumference ratio (WHR), used as an index of body fat distribution, and the areas of insulin (r = 0.55; P less than 0.001) and C-peptide (r = 0.51; P less than 0.001). SHBG and free androgen index (FAI) were also significantly related to these areas. The peripheral C-peptide/insulin molar ratio has been assumed to reflect changes in hepatic insulin extraction while the corrected C-peptide response reflects beta-cell function. WHR was negatively related to this ratio (r = -0.44; P less than 0.005) and SHBG showed a positive correlation (r = 0.34; P less than 0.05). Stepwise multiple regression analysis revealed that the 2-h insulin and C-peptide values and both curve areas can be explained up to 40-80% by sex hormones and anthropometric variables. Also the C-peptide/insulin molar ratio is dependent in a first step on WHR (r2 = 0.23; P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Hormone-producing tumors of the ovary

The ovary is an endocrine organ that gives rise to a wide variety of neoplastic and tumorlike nonneoplastic conditions, some of which are associated with endocrine activity. The hormones produced may be steroidal or nonsteroidal. The ovary is unique among endocrine organs in reacting to the presence of nonendocrine tumors within it by abnormal or inappropriate production of sex steroidal hormones. A classification of hormone-producing ovarian lesions is proposed based on the World Health Organization's histologicai typing of ovarian tumors.

Acanthosis nigricans in obese women with the polycystic ovary syndrome: disease spectrum not distinct entity

Fasting and stimulated insulin concentrations in four patients with acanthosis nigricans and polycystic ovary syndrome were compared with four patients, matched for weight and ovarian morphology, without acanthosis. The median fasting serum insulin concentrations were 114.2 and 25.1 mU/l in the respective groups (P = 0.02). One additional patient was investigated before and after an 18% increase in weight which resulted in a 170% increase in fasting insulin concentrations and the development of acanthosis nigricans. These observations suggest that there is variation between individuals in the degree of obesity that results in the development of acanthosis and that obese patients with this skin condition represent the severe end of the spectrum of the polycystic ovary syndrome.

The use of the intravenous glucose tolerance test to evaluate nonobese hyperandrogenemic women

To better define the association of hyperandrogenemia and insulin resistance, we evaluated nonobese, nonacanthotic hyperandrogenemic women utilizing intravenous glucose tolerance tests (IVGTT). Six women (group 1) all of whom had elevated serum testosterone (T) and were less than 5% above their ideal body weight for height underwent IVGTTs. A control group (group 2, n = 5) with equivalent weight and height but normal levels of T were similarly tested. The T values (normal 0.1 to 0.6 ng/mL) in group 1 (0.93 +/- 0.05 ng/mL, mean +/- SEM) were significantly different from those in group 2 (0.34 +/- 0.03 ng/mL). Area under the curve (AUC) was calculated for the glucose and insulin values. The glucose AUC for group 1 (15,000 +/- 1,100) was not significantly different from the glucose AUC for group 2 (15,853 +/- 788). Interestingly, the insulin AUC for group 1 (3,829 +/- 583) was not significantly different from the insulin AUC for group 2 (2,987 +/- 456). Within group 1, a correlation between serum T and insulin AUC could not be established. We conclude that in these nonobese, nonacanthotic hyperandrogenemic females, although individual variation exists, collectively a significantly increased insulin response to an IVGTT challenge cannot be demonstrated. This data further challenges the concept of androgens being etiologic in insulin resistance.

Medical therapy for the syndrome of familial virilization, insulin resistance, and acanthosis nigricans

In the syndrome of familial virilization, insulin resistance, and acanthosis nigricans, the interrelationships are not understood. Twin sisters were studied, along with a lesser affected sister and mother. They manifested amenorrhea, hirsutism, masculinization, hypertension, hyperinsulinemia, hypertriglyceridemia, and hyperprolactinemia. Medical therapy with a gonadotropin-releasing hormone agonist plus an antiandrogen resulted in reversal of the hirsutism, yet with preservation of potential fertility. In response to luteinizing hormone (LH) and follicle-stimulating hormone suppression, there was normalization of the serum androgens, but not of the hyperinsulinemia, hypertriglyceridemia, hyperprolactinemia, hypertension, or acanthosis nigricans.

CONCLUSIONS

(1) This syndrome may be familial. (2) Medical therapy for the virilization is successful. (3) The hyperandrogenemia is primarily LH dependent and not primarily insulin dependent, although insulin may have an amplification effect. (4) Hyperinsulinemia, hypertriglyceridemia, hyperprolactinemia, and the hypertension are not androgen dependent.

The relationship of insulin sensitivity and metabolic clearance of insulin to adiposity and sex hormone binding globulin

Previous studies have shown that sex hormone binding globulin (SHBG) is negatively associated with insulin concentrations in premenopausal women. We determined insulin sensitivity (SI) and clearance (KI) in 8 non-obese men and 13 nonobese premenopausal women using the minimal model of Bergman and colleagues. Insulin clearance and insulin sensitivity were strongly correlated (p less than 0.05). SHBG was positively correlated with SI (i.e., individuals with high levels of SHBG had greater insulin sensitivity) in both men (r = .738, p less than 0.05) and women (r = .577, p less than 0.06). Insulin clearance was also positively correlated with SHBG in men (r = .619) and in women (r = .476) (0.05 less than p less than 0.10). Since obese subjects have both lower SHBG concentrations and decreased insulin sensitivity, we examined the effect of correcting for adiposity by partial correlation analyses. SHBG was not associated with KI after adjustment for BMI. SHBG was still positively correlated with SI in both men (r = .708) (p less than 0.06) and women (r = 0.541) (p less than 0.06), suggesting that the relationship between SHBG and insulin sensitivity is not confounded by obesity. Thus, the relationship of androgenicity with insulin sensitivity (but not insulin clearance) was independent of adiposity.

Insulin administration alters gonadal steroid metabolism independent of changes in gonadotropin secretion in insulin-resistant women with the polycystic ovary syndrome

We have investigated the hypothesis that hyperinsulinemia may cause the polycystic ovary syndrome (PCO) by directly stimulating gonadal steroidogenesis and/or gonadotropin secretion. 10 insulin-resistant women with PCO and 5 age- and weight-matched ovulatory normal women had pulsatile gonadotropin release, gonadotrope sensitivity to gonadotropin-releasing hormone, and sex hormone levels studied on two consecutive study days, basally and during the infusion of insulin (mean +/- SEM steady state insulin levels, 1,254 +/- 63 microU/ml PCO vs. 907 +/- 92 microU/ml normal, P less than or equal to 0.01). Insulin acutely increased mean delta (6 h minus prestudy) levels of androstenedione (A) (P less than or equal to 0.001) and estradiol (E2) (P less than or equal to 0.05) and decreased mean plasma pool (0-6 h) levels of testosterone (T) (P less than 0.05), nonsex hormone binding globulin-bound T (P less than 0.05), and dihydrotestosterone (P less than or equal to 0.01) in the PCO women. Insulin also decreased mean plasma 6 h A to estrone (E1) ratios and increased 6 h E1 levels (both P less than or equal to 0.05) in the PCO women. There were significant sequence effects (insulin + day) in the PCO women on T/E2 ratios, indicating a carryover action of insulin. Insulin had no effects on gonadotropin release in the PCO women. In the normal women, the only significant change was an insulin or study day effect that increased mean 6 h E2 levels (P less than or equal to 0.01). There were significant spontaneous decreases in mean luteinizing hormone (p less than 0.05) and follicle-stimulating hormone levels (p less than or equal to 0.01) in the PCO but not the normal women on the second day of study. This study indicates that insulin can directly alter peripheral sex hormone levels independent of changes in gonadotropin release in insulin-resistent PCO women. Insulin decreased the levels of potent androgens in PCO women and did not increase androgen levels in normal women, arguing against a simple, direct causal relationship between hyperinsulinemia and hyperandrogenism in PCO.

Association of decreased sex hormone binding globulin and cardiovascular risk factors

Sex hormones play a major role in determining the risk of cardiovascular disease. While earlier studies have shown that reduced sex hormone binding globulin (SHBG) is associated with increased glucose and insulin concentrations in premenopausal women, few data exist on the relationship of SHBG to other cardiovascular risk factors in women. We hypothesized that decreased SHBG would be associated with an atherogenic pattern of cardiovascular risk factors. We measured total testosterone, total estradiol and SHBG, lipids and lipoproteins, glucose and insulin, and systolic and diastolic blood pressure in 96 premenopausal women. Although total testosterone and total estradiol were not related to cardiovascular risk factors, SHBG was negatively associated with triglyceride concentration (r = -0.37) and positively associated with high density lipoprotein cholesterol (HDLC) (r = 0.42). After adjustment for overall adiposity (body mass index) and upper body adiposity (as measured by the ratio of waist-to-hip circumferences), SHBG was still positively related to HDLC, but not to triglyceride. Adjustment for insulin abolished the relationship between SHBG and triglyceride levels, but did not alter the relationship between SHBG and HDLC. Sex hormones were not related to either systolic or diastolic blood pressure.

Alterations in carbohydrate metabolism as they apply to reproductive endocrinology

This review has characterized the current state of knowledge of four clinical situations in which an interrelationship of gynecology, endocrinology and carbohydrate metabolism is recognized. The literature contains conflicting descriptions of changes in glucose homeostasis during the menstrual cycle and while using birth control pills. Physiologic changes in receptor number have been demonstrated in each of these situations, so failure to observe differences using glucose tolerance testing may reflect an in vivo homeostatic response to changes in these hormone levels. Thus, in vivo identification of alterations in carbohydrate metabolism induced by endogenous or exogenous steroids may require utilization of models that prevent these homeostatic mechanisms. The association between hyperandrogenism and hyperinsulinism has been better characterized, but the relationship is complicated by the frequent coexistence of obesity. The association may be due to insulin-stimulated ovarian androgen production, and insulin insensitivity may reflect a postreceptor defect. Insulin and its metabolic effects have also been implicated in ovulatory dysfunction in women with diabetes mellitus and identified as a factor affecting all levels of the hypothalamic-pituitary-ovarian axis. A clearer understanding of these relationships and their application to clinical management await further study.

The role of hyperinsulinemia in the pathogenesis of ovarian hyperandrogenism

The evidence that supports the hypothesis that insulin and LH both regulate ovarian androgen production was presented. The most dramatic clinical example of the association between hyperinsulinemia and hyperandrogenism is the HAIR-AN syndrome. Our hypothesis is that, in the HAIR-AN syndrome, the severe insulin resistance causes a compensatory hyperinsulinemia, which stimulates ovarian androgen production if adequate LH is present. The acanthosis nigricans is an epiphenomenon of the syndrome. Acanthosis nigricans is a dermatologic manifestation of severe insulin resistance. In vitro evidence suggests that insulin and IGF-I stimulate androgen production in incubations of human stroma and theca. The stromatropic effects of insulin may sensitize the stroma to the stimulatory effects of LH. In some hyperandrogenic-insulin-resistant women, a glucose load appears to produce an acute rise in circulating androgens. The magnitude of the rise in circulating androgens is proportional to the magnitude of the insulin response to the glucose load. These data suggest that hyperinsulinemia may play a central role in the development of ovarian hyperandrogenism.

Hyperandrogenism, insulin resistance, acanthosis nigricans, and systemic lupus erythematosis associated with insulin receptor antibodies

We report a young woman with systemic lupus erythematosis (SLE) who developed diabetes secondary to extreme insulin resistance, associated with severe hyperandrogenism and acanthosis nigricans. Her insulin resistance was found to be associated with high titers of insulin receptor antibodies. The hyperandrogenism has been favourably influenced by cyclical treatment with cyproterone acetate and ethinyl oestradiol, but the insulin resistance and acanthosis nigricans have remained unmodified after 15 months of follow up.

The relationship of sex hormones to hyperinsulinemia and hyperglycemia

Mexican-Americans, a high-risk population for non-insulin-dependent diabetes mellitus (NIDDM), have been previously reported to have decreased levels of sex-hormone-binding globulin (SHBG). We measured total testosterone, total estradiol and SHBG, glucose and insulin in premenopausal women (58 Mexican-Americans and 38 non-Hispanic whites) as part of the San Antonio Heart Study, a population-based study of cardiovascular risk factors. Although total estradiol and total testosterone were, in general, not correlated with metabolic variables, SHBG was negatively correlated with glucose and insulin. After adjustment for body mass index (BMI), ratio of waist-to-hip circumference (WHR) and ratio of subscapular-to-triceps skinfold (Centrality Index), SHBG was still significantly correlated with insulin concentrations (P less than .001). Since Mexican-Americans were previously reported to be more hyperinsulinemic than non-Hispanic whites, we examined the effect of adjusting for SHBG on insulin levels in this small population. While unadjusted insulin concentrations in Mexican-Americans were higher than in non-Hispanic whites (354 microU/mL v 236 microU/mL, respectively, P = .009), adjustment for BMI, WHR, and centrality index reduced the ethnic difference in insulin levels considerably (P = .014). However, only after adjusting for SHBG as well, did the ethnic difference in insulin levels became nonsignificant. Our data suggest that alterations in sex hormones and SHBG in particular may be related to the hyperinsulinemia and the high rates of NIDDM in Mexican-Americans.

Hyperinsulinemia, upper body adiposity, and cardiovascular risk factors in non-diabetics

Previous studies have suggested that hyperinsulinemia and upper body adiposity are each separately associated with elevated BP and triglyceride (TG) levels, and with lower high density lipoprotein (HDL) cholesterol levels. The joint effect of hyperinsulinemia and upper body adiposity on lipids, lipoproteins, and BP, however, has not been previously studied. We hypothesized that the effect of body fat distribution on cardiovascular risk factors might be mediated through hyperinsulinemia. We measured BP, lipids and lipoproteins, HDL subfractions, and insulin and glucose concentrations as part of the San Antonio Heart Study, a population-based study of diabetes and cardiovascular risk factors. Insulinemia and glycemia were assessed as the sum of the fasting, half-hour, one-hour, and two-hour insulin and glucose levels, respectively, measured during a standardized oral glucose tolerance test. Individuals who had diabetes according to National Diabetes Data Group criteria were excluded from the analyses. In univariate analyses, both hyperinsulinemia and waist-to-hip ratio (WHR), a measure of upper body adiposity, were positively associated with TG and negatively associated with total HDL and HDL2 cholesterol levels. However, when the effects of glycemia and insulinemia were controlled for by analysis of variance, WHR was no longer significantly related to TG levels. By contrast, WHR continued to be inversely related to total HDL and HDL2 cholesterol even after adjustment for glycemia and insulinemia. Hyperinsulinemia was only weakly related to HDL cholesterol. These results suggest that insulinemia and glycemia might mediate the effects of upper body adiposity on TG, although not on HDL and HDL2 cholesterol. Hyperinsulinemia was also positively associated with diastolic and systolic BP in men.

Effect of chronically elevated androgen or estrogen on the glucose tolerance test and insulin response in female rhesus monkeys

Insulin concentrations, in response to an intravenous glucose bolus after a 24-hour fast, have been studied in female rhesus monkeys in which the circulating levels of androstenedione and testosterone or estrone and estradiol have been increased for as long as 4 1/2 years. No significant differences were observed in the basal insulin or C-peptide concentrations in the androgen or estrogen-treated animals compared with each other or with normal cycling, nontreated control animals. The insulin and C-peptide responses to intravenous glucose were similar in control and androgen-treated monkeys. Compared with both the control and androgen-treated monkeys, the responses of the estrogen-treated monkeys tended to be lower but were not significantly different. The glucose disappearance rate after the intravenous glucose bolus was not significantly different in androgen and control monkeys but was significantly slower during the initial 30 minutes in the estrogen-treated monkeys compared with both the control and androgen-treated monkeys. These studies suggest that chronically elevated androgen levels in the mature female subhuman primate do not lead to insulin resistance or overt glucose intolerance.

Spectrum of endocrine abnormalities associated with acanthosis nigricans

Acanthosis nigricans is a marker for disorders of insulin action, endocrine abnormalities, and cancer of internal organs. To evaluate the clinical significance of this marker the systemic alterations and clinical features of 26 patients with acanthosis nigricans seen at two institutions were reviewed. Most subjects affected by acanthosis nigricans were female (20 patients), Caucasian (22 patients), in the third decade of life (13 patients), and overweight (24 patients greater than 120 percent ideal body weight). Gonadal disease, present in 17 patients, was expressed as polycystic ovary syndrome (11 cases), disorders of prolactin secretion (two cases, one with polycystic ovary syndrome), streak gonads (one case), and hypogonadism of the male (four cases). Thyroid disease and tinea versicolor were present in four patients each. Three patients were receiving insulin therapy for diabetes mellitus, and in two additional patients diabetes mellitus was detected during the diagnostic workup. All patients had elevated fasting insulin levels; most of them also had an exaggerated insulin response to a glucose load. Two of 18 patients tested had antibodies against the insulin receptor in the circulation. Skin biopsy of acanthosis nigricans lesions from all 26 patients showed a typical pattern of hyperkeratosis, acanthosis, and epidermal papillomatosis. Colloidal iron staining showed glycosaminoglycan infiltration of the papillary dermis (21 of 21 cases), consisting mainly of hyaluronic acid. It is concluded that: (1) hyperinsulinenemia and local dermal glycosaminoglycan deposition are regular features in acanthosis nigricans and (2) patients with acanthosis nigricans should be screened for diabetes mellitus, gonadal disease, and hypothyroidism.

Acanthosis nigricans

Acanthosis nigricans (AN) is a well-defined skin disorder characterized by velvety hyperkeratotic macules that can be accompanied by various degrees of pigmentation. Other manifestations of AN are marked papillomatous growths and deep skin markings. These changes can affect the entire skin but preferentially are observed in the axilla, neck, genitals, and oral cavity. The presence of AN around and within the oral cavity as well as its well-known association with internal malignant conditions, especially adenocarcinoma of the stomach, and/or its association with insulin resistance, has prompted this review article, which emphasizes the oral manifestations of AN.

Elevated serum dehydroepiandrosterone sulfate levels in patients with insulin resistance, hirsutism, and acanthosis nigricans

The association of insulin resistance, hyperandrogenism, and acanthosis nigricans is well established. The ovary is thought to be the site of the excess androgen production. The purpose of this study was to assess the adrenal contribution to the hyperandrogenic state in these women. Twenty-three patients presenting with the combination of hyperinsulinemia, elevated testosterone (T) levels, and acanthosis nigricans were investigated for the source of the increased androgen production. Twelve patients had elevated serum dehydroepiandrosterone sulfate (DS) levels (high DS group) suggestive of increased adrenal androgen production. Eleven patients had normal DS levels (normal DS group). Both normal DS and high DS groups had similar basal serum insulin levels and similar insulin response curves after a 3-hour, 75-gm, oral glucose tolerance test. No correlation was found between serum T or DS levels and either basal serum insulin levels or the area under the insulin response curve. These data suggest that DS levels are frequently elevated in patients with hirsutism, acanthosis, and hyperinsulinemia. Furthermore, the lack of association between serum DS and serum insulin levels suggests that insulin does not directly affect adrenal androgen production, or vice versa.

Remission of acanthosis nigricans, hypertrichosis, and Hashimoto's thyroiditis with thyroxine replacement

Hypothyroidism is not commonly associated with acanthosis nigricans (AN). We examined a 13-year-old girl with AN, hypertrichosis, and Hashimoto's thyroiditis. Overt biochemical hypothyroidism, thyroid enlargement, and positive titers of antimicrosomal and antithyroglobulin antibodies confirmed Hashimoto's thyroiditis. Both AN and hypertrichosis resolved with thyroid hormone replacement. There was no evidence of insulin resistance, polycystic ovarian disease, lipoatrophy, or other endocrine dysfunction, or of malignancy. In two patients from the literature with AN and hypothyroidism, AN was attributed to associated thyroid carcinoma or insulin resistance, rather than coexisting hypothyroidism. Since the skin lesions improved with thyroid hormone therapy in those two patients and in ours, hypothyroidism appears to be directly involved in the pathogenesis of AN.

Insulin resistance with acanthosis nigricans: the roles of obesity and androgen excess

The roles of hyperandrogenemia and obesity in the syndrome of severe insulin resistance with acanthosis nigricans were evaluated in studies of 11 females with this condition. Our results in these subjects were compared to evaluations of control subjects matched for degree of androgen excess or obesity. Fasting insulin levels were 3-, 5-, and 15-fold higher in the obese (OB), hyperandrogenemic (HO), and acanthosis nigricans (AN) groups, respectively, when compared to normal females. Responsiveness to a standard bolus of exogenous insulin was 78% of normal in the OB group, 40% of normal in the HO group, and 30% of normal in the AN group. Insulin binding to monocytes from both the OB group, and the HO group was modestly diminished primarily due to decreased receptor number. As a group, AN subjects when compared to either normal or weight-matched controls, demonstrated a significant decrease in monocyte insulin binding predominantly due to a decrease in receptor number. However, two patients in the AN group had normal insulin binding suggesting a postreceptor mechanism for the insulin resistance in at least some of these subjects. In vivo glucose utilization insulin dose response curves were determined in 3 acanthotic subjects using the euglycemic clamp technique. All 3 of these subjects had a right shift of the curve and diminished maximal utilization, consistent with combined receptor and postreceptor defects in insulin action. In evaluating the relationship between hyperandrogenemia, insulin resistance, and acanthosis nigricans, significant correlations among basal levels of plasma insulin, and both testosterone and androstenedione were demonstrated.(ABSTRACT TRUNCATED AT 250 WORDS)