The relationship between sex steroids and sex-hormone-binding globulin in plasma in physiological and pathological conditions

Genetic analyses implicate complex links between adult testosterone levels and health and disease

BACKGROUND

Testosterone levels are linked with diverse characteristics of human health, yet, whether these associations reflect correlation or causation remains debated. Here, we provide a broad perspective on the role of genetically determined testosterone on complex diseases in both sexes.

METHODS

Leveraging genetic and health registry data from the UK Biobank and FinnGen (total N = 625,650), we constructed polygenic scores (PGS) for total testosterone, sex-hormone binding globulin (SHBG) and free testosterone, associating these with 36 endpoints across different disease categories in the FinnGen. These analyses were combined with Mendelian Randomization (MR) and cross-sex PGS analyses to address causality.

RESULTS

We show testosterone and SHBG levels are intricately tied to metabolic health, but report lack of causality behind most associations, including type 2 diabetes (T2D). Across other disease domains, including 13 behavioral and neurological diseases, we similarly find little evidence for a substantial contribution from normal variation in testosterone levels. We nonetheless find genetically predicted testosterone affects many sex-specific traits, with a pronounced impact on female reproductive health, including causal contribution to PCOS-related traits like hirsutism and post-menopausal bleeding (PMB). We also illustrate how testosterone levels associate with antagonistic effects on stroke risk and reproductive endpoints between the sexes.

CONCLUSIONS

Overall, these findings provide insight into how genetically determined testosterone correlates with several health parameters in both sexes. Yet the lack of evidence for a causal contribution to most traits beyond sex-specific health underscores the complexity of the mechanisms linking testosterone levels to disease risk and sex differences.

Accurate measurement of total and free testosterone levels for the diagnosis of androgen disorders

The circulating concentrations of total and free testosterone vary substantially in people over time due to biologic factors as well as due to measurement variation. Accurate measurement of total and free testosterone is essential for making the diagnosis of androgen disorders. Total testosterone should ideally be measured in a fasting state in the morning using a reliable assay, such as liquid chromatography tandem mass spectrometry, in a laboratory that is certified by an accuracy-based benchmark. Free testosterone levels should be measured in men in whom alterations in binding protein concentrations are suspected or in whom total testosterone levels are only slightly above or slightly below the lower limit of the normal male range for testosterone.

A Reappraisal of Testosterone's Binding in Circulation: Physiological and Clinical Implications

In the circulation, testosterone and other sex hormones are bound to binding proteins, which play an important role in regulating their transport, distribution, metabolism, and biological activity. According to the free hormone hypothesis, which has been debated extensively, only the unbound or free fraction is biologically active in target tissues. Consequently, accurate determination of the partitioning of testosterone between bound and free fractions is central to our understanding of how its delivery to the target tissues and biological activity are regulated and consequently to the diagnosis and treatment of androgen disorders in men and women. Here, we present a historical perspective on the evolution of our understanding of the binding of testosterone to circulating binding proteins. On the basis of an appraisal of the literature as well as experimental data, we show that the assumptions of stoichiometry, binding dynamics, and the affinity of the prevailing models of testosterone binding to sex hormone-binding globulin and human serum albumin are not supported by published experimental data and are most likely inaccurate. This review offers some guiding principles for the application of free testosterone measurements in the diagnosis and treatment of patients with androgen disorders. The growing number of testosterone prescriptions and widely recognized problems with the direct measurement as well as the computation of free testosterone concentrations render this critical review timely and clinically relevant.

A systematic review and meta-analysis of physical activity and endometrial cancer risk

Physical activity is related to decreased endometrial cancer risk. However, a comprehensive investigation of activity domains, intensities, time periods in life, and potential interaction with body mass index is unavailable. We performed a meta-analysis of physical activity and endometrial cancer studies published through October 2014. We identified 33 eligible studies comprising 19,558 endometrial cancer cases. High versus low physical activity was related to reduced endometrial cancer risk [relative risk (RR) = 0.80; 95% confidence interval (CI) 0.75-0.85]. The corresponding RRs for recreational activity, occupational activity, household activity, and walking were 0.84 (95% CI 0.78-0.91), 0.81 (95% CI 0.75-0.87), 0.70 (95% CI 0.47-1.02), and 0.82 (95% CI 0.69-0.97), respectively (Pdifference). Walking/biking for transportation, walking for recreation, and walking without specification revealed summary RRs of 0.70 (95% CI 0.58-0.85), 0.94 (95% CI 0.76-1.17), and 0.88 (95% CI 0.52-1.50), respectively (Pdifference). Inverse associations were noted for light (RR 0.65; 95% CI 0.49-0.86), moderate to vigorous (RR 0.83; 95 % CI 0.71-0.96), and vigorous activity (RR 0.80; 95% CI 0.72-0.90; (Pdifference). A statistically significant inverse relation was found for postmenopausal (RR 0.81; 95% CI 0.67-0.97), but not premenopausal women (RR 0.74; 95% CI 0.49-1.13; (Pdifference). Physical activity performed during childhood/adolescence, young adulthood/midlife, and older age yielded RRs of 0.94 (95% CI 0.82-1.08), 0.77 (95% CI 0.58-1.01), and 0.69 (95% CI 0.37-1.28), respectively (Pdifference). An inverse relation was evident in overweight/obese (RR 0.69; 95% CI 0.52-0.91), but not normal weight women (RR 0.97; 95% CI 0.84-1.13; (Pdifference). In conclusion, recreational physical activity, occupational physical activity, and walking/biking for transportation are related to decreased endometrial cancer risk. Inverse associations are evident for physical activity of light, moderate to vigorous, and vigorous intensities. The inverse relation with physical activity is limited to women who are overweight or obese.

Apolipoprotein B/A1 ratio is associated with free androgen index and visceral adiposity and may be an indicator of metabolic syndrome in male children and adolescents

OBJECTIVE

A high apolipoprotein B/apolipoprotein A1 (apoB/A1) ratio is strongly associated with cardiometabolic diseases. However, few studies have examined this ratio in children and adolescents. The aim of our study was to determine significant factors related to the apoB/A1 ratio and examine its association with paediatric metabolic syndrome.

PATIENTS AND METHODS

Sixty-seven male children and adolescents were recruited. We measured anthropometric parameters, fat areas by abdominal computed tomography, fasting glucose, insulin, lipid profiles, apoB, apoA1, adiponectin, free androgen index (FAI) and oestradiol.

RESULTS

Thirty per cent of participants (n = 20) were identified as having paediatric metabolic syndrome. The apoB/A1 ratio was significantly correlated with BMI z-score, waist circumference, waist-to-hip ratio (WHR), waist-to-height ratio, abdominal fat areas, total cholesterol, triglycerides, LDL-cholesterol, HDL-cholesterol, adiponectin and leptin. In addition to lipid profiles, WHR was identified as a significant independent variable correlated with the apoB/A1 ratio. Obese boys with a high FAI (>75th percentile) had significantly lower adiponectin and higher apoB/A1 ratios than those with a low FAI. The apoB/A1 ratio was higher in subjects with high visceral fat (>50th percentile) and a high FAI when compared with subjects with low visceral fat and a low FAI. The prevalence of paediatric metabolic syndrome was significantly associated with increasing tertiles of the apoB/A1 ratio (highest tertile; odds ratio = 18·8 [95% confidence interval = 1·8-198·8], P < 0·05).

CONCLUSION

ApoB/A1 ratio was significantly higher in viscerally obese male children and adolescents with high levels of FAI and was associated with increased frequency of paediatric metabolic syndrome.

Serum leptin levels, hormone levels, and hot flashes in midlife women

OBJECTIVE

To examine the associations between serum leptin levels, sex steroid hormone levels, and hot flashes in normal weight and obese midlife women.

DESIGN

Cross-sectional study.

SETTING

University clinic.

PATIENT(S)

201 Caucasian, nonsmoking women aged 45 to 54 years with a body mass index of <25 kg/m2 or >or=30 kg/m2.

INTERVENTION(S)

Questionnaire, fasting blood samples.

MAIN OUTCOME MEASURE(S)

Serum leptin and sex steroid hormone levels.

RESULT(S)

Correlation and regression models were performed to examine associations between leptin levels, hormone levels, and hot flashes. Leptin levels were associated with BMI, with "ever experiencing hot flashes" (questionnaire), with hot flashes within the last 30 days, and with duration of hot flashes (>1 year, P=.03). Leptin was positively correlated with testosterone, free testosterone index, and free estrogen index and inversely associated with levels of sex hormone-binding globulin. In women with a body mass index>or=30 kg/m2, leptin levels no longer correlated with testosterone levels.

CONCLUSION(S)

Serum leptin levels are associated with the occurrence and duration of hot flashes in midlife women; however, no correlation was found between leptin and serum estradiol.

Androgen insensitivity syndrome

Over the past four years, major advances in the understanding of the aetiology and pathogenesis of the androgen insensitivity syndrome (AIS) have occurred. This review aims to summarize current information on clinical, diagnostic, therapeutic and molecular aspects of AIS.

Genetic polymorphisms, hormone levels, and hot flashes in midlife women

OBJECTIVE

Hot flashes disrupt the lives of millions of women each year. Although hot flashes are a public health concern, little is known about risk factors that predispose women to hot flashes. Thus, the objective of this study was to examine whether sex steroid hormone levels and genetic polymorphisms in hormone biosynthesis and degradation enzymes are associated with the risk of hot flashes.

METHODS

In a cross-sectional study design, midlife women aged 45-54 years (n=639) were recruited from Baltimore and its surrounding counties. Participants completed a questionnaire and donated a blood sample for steroid hormone analysis and genotyping. The associations between genetic polymorphisms and hormone levels, as well as the associations between genetic polymorphisms, hormone levels, and hot flashes were examined using statistical models.

RESULTS

A polymorphism in CYP1B1 was associated with lower dehydroepiandrosterone-sulfate (DHEA-S) and progesterone levels, while a polymorphism in CYP19 (aromatase) was associated with higher testosterone and DHEA-S levels. Lower progesterone and sex hormone binding globulin levels, lower free estradiol index, and a higher ratio of total androgens to total estrogens were associated with the experiencing of hot flashes. A polymorphism in CYP1B1 and a polymorphism in 3betaHSD were both associated with hot flashes.

CONCLUSION

Some genetic polymorphisms may be associated with altered levels of hormones in midlife women. Further, selected genetic polymorphisms and altered hormone levels may be associated with the risk of hot flashes in midlife women.

Relation of body mass and sex steroid hormone levels to hot flushes in a sample of mid-life women

OBJECTIVE

Previous studies indicate that obesity is associated with a higher risk of experiencing hot flushes in mid-life women. The reasons for this association are unknown, although altered hormone levels have been associated with both hot flushes and obesity. Thus, this current study tested the hypothesis that obesity is associated with hot flushes in mid-life women through a mechanism involving levels of total and free androgen, free estrogen, progesterone, and sex hormone binding globulin (SHBG).

METHODS

Women aged 45-54 years were recruited from Baltimore and its surrounding counties. Each participant (n=628) was weighed, measured, completed a questionnaire, and provided a blood sample that was used to measure estradiol, estrone, testosterone, androstenedione, dehydroepiandrosterone sulfate, progesterone, and SHBG.

RESULTS

Obese mid-life women (body mass index (BMI)>or=30.0 kg/m2) had significantly higher testosterone, and lower estradiol, estrone, progesterone, and SHBG levels than normal-weight mid-life women (BMI<or=24.9 kg/m2) after adjustment for age, race, smoking, and number of days since last menstrual period. The association between obesity and hot flushes was no longer significant after adjustment for estrogens and progesterone, and/or SHBG.

CONCLUSION

These data suggest that obesity may be associated with hot flushes through a mechanism involving multiple hormones and SHBG.

Current alcohol use, hormone levels, and hot flashes in midlife women

Current alcohol use is associated with a lower risk of hot flashes through a mechanism that does not include changes in sex steroid hormone levels.

Sex-related differences between adiponectin and insulin resistance in schoolchildren

OBJECTIVE

To study the effect of body composition and adiponectin on insulin resistance and beta-cell function in schoolchildren during puberty.

RESEARCH DESIGN AND METHODS

Plasma adiponectin level and its relationships with insulin sensitivity and beta-cell function were analyzed in 500 randomly recruited nondiabetic Taiwanese schoolchildren (245 boys and 255 girls) aged 6-18 years in a national survey program for diabetes in 1999. Insulin resistance and beta-cell function were evaluated by homeostasis model assessment (HOMA). Plasma adiponectin concentrations were determined with radioimmunoassay.

RESULTS

Plasma glucose levels remained stable, whereas insulin resistance increased with a compensatory rise in beta-cell function during this period. A transient drop of adiponectin level with a trough at 10-12 years was found in boys but not in girls. This pubertal drop of adiponectin levels in boys coincides with the sharp rise in testosterone concentration. A negative correlation between testosterone levels and adiponectin concentration was also noted in boys (r = -0.142, P = 0.032). Plasma adiponectin levels correlated inversely with relative body weight, fasting insulin concentrations, and insulin resistance index by HOMA in boys aged 15-18 years and in girls aged 11-14 years. No association was observed between adiponectin levels and beta-cell function by HOMA.

CONCLUSIONS

There is a transient drop in the level of adiponectin during male puberty, correlated with the increase in testosterone level in boys. Plasma adiponectin levels were inversely correlated with obesity and insulin resistance in boys and girls during the pubertal period.

The effect of long-term glucocorticoid therapy on glucocorticoid receptor content and on steroid response to ACTH

The effect of long-term glucocorticoid therapy for systemic diseases on glucocorticoid receptor (GR) content and on basal and ACTH-stimulated levels of plasma and salivary cortisol 17 alpha-hydroxy-progesterone, androstenedione, 11 beta-hydroxyandrostenedione, DHEA, its sulfate and sex hormone-binding globulin (SHBG), as well as on basal levels of aldosterone, was investigated in a group of 24 children treated with prednisone for at least 8 months. The therapy was interrupted 24 h before the ACTH test and before plasma and saliva sampling. The control group consisted of 21 healthy children of corresponding age and sex. The patients were divided into two subgroups with normal and subnormal basal cortisolemia, they also differed in their response to ACTH. The GR levels in patient groups were indistinguishable from those found in controls. No correlation was found between GR content and basal levels of the above steroids or their response to ACTH. The best markers, apart from basal cortisolemia, for evaluation of the degree of suppression of adrenal function appeared to be the response of salivary (but not of plasma) cortisol and 17 alpha-hydroxy-progesterone to ACTH. Surprisingly, significantly lower levels of SHBG levels, which rose markedly after ACTH, were found in all the patients.

Hormonal and clinic evaluation of patients with moderate body hair growth

Plasma prolactin (PRL), gonadotropins (FSH, LH), estradiol-17 beta (E2), progesterone (P), total testosterone (T), sex steroid binding protein (SBP), T/SBP index, cortisol (F), 17-OH-progesterone (17OH-P), dehydroepiandrosterone sulphate (DHEA-S) and androstenedione (A), were measured in 50 fertile non-obese women presenting with moderate body hair growth and in 30 matched controls. DHEA-S and PRL were significantly higher (P < 0.002, P < 0.001, respectively) and SBP was lower (P < 0.001) in patients than in controls. Regression analyses showed that PRL levels were independent of the other parameters, while a negative correlation was found between DHEA-S and SBP values. Since the decision to treat a woman with mild body hair growth is usually a clinical one, PRL behaviour has to be taken into account before deciding the type of treatment. Clinical improvement was observed in subjects treated with ethynylestradiol plus desogestrel or plus cyproterone acetate, so as to produce an increase in SBP rather than a decrease in DHEA-S.

Dehydroepiandrosterone sulfate and other possible influencing factors that modulate sex hormone-binding globulin levels in the hirsute patient

This study was designed to investigate the most important factors affecting serum concentrations of sex hormone-binding globulin (SHBG) in women with hirsutism. We compared endocrine profiles based on biochemical measurements of LH, FSH, oestradiol, testosterone (T), prolactin, 17-hydroxy-progesterone, dehydroepiandrosterone sulphate (DHEAS), SHBG, cortisol and insulin in the follicular phase in 32 healthy women and 52 patients. The study group was subdivided according to SHBG levels into Group A (low level) and Group B (high level). Significant differences between Groups A and B were found in DHEAS and T levels, but not in body mass index or insulinaemia. There was a relationship between DHEAS and SHBG levels (r = 0.51) and between T and SHBG (r = 0.31). We conclude that DHEAS may be a significant modulator of SHBG in the female hirsute patient, an observation seldom mentioned in previous reports.

Sex hormone binding globulin: origin, function and clinical significance

Sex hormone binding globulin (SHBG) is a glycoprotein possessing high affinity binding for 17 beta-hydroxysteriod hormones such as testosterone and oestradiol. It is probably synthesized in the liver, plasma concentrations being regulated by, amongst other things, androgen/oestrogen balance, thyroid hormones, insulin and dietary factors, it is involved in transport of sex steroids in plasma and its concentration is a major factor regulating their distribution between the protein-bound and free states. Its detailed role in the delivery of hormones to target tissues is not yet clear. Plasma SHBG concentrations are affected by a number of different diseases, high values being found in hyperthyroidism, hypogonadism, androgen insensitivity and hepatic cirrhosis in men. Low concentrations are found in myxoedema, hyperprolactinaemia and syndromes of excessive androgen activity. Concentrations are also affected by drugs such as androgens, oestrogens, thyroid hormones and anti-convulsants. Measurement of SHBG is useful in the evaluation of mild disorders of androgen metabolism and enables identification of those women with hirsutism who are more likely to respond to oestrogen therapy. Testosterone:SHBG ratios correlate well with both measured and calculated values of free testosterone and help to discriminate subjects with excessive androgen activity from normal individuals.

The ovary-suppression test in the evaluation of hyperandrogenemia

Forty hyperandrogenemic women were investigated in order to determine whether the source of androgen excess could be attached to a dysfunction of the ovary or the adrenal cortex with a higher degree of accuracy when both steroid-producing organs were subjected to a supposedly specific suppression test. Dexamethasone (DXM) was administered at a dose of 2 mg for 2 days. The ovary-suppression test (OST) was carried out after a combined preparation containing 35 micrograms of ethinyl estradiol and 2 mg of cyproterone acetate (EE-CPA) had been taken for 2-3 weeks. Before and after the tests, the serum levels of testosterone (T), free testosterone (fT), DHEA-S and SHBG were determined. Serum T was lowered by DXM and EE-CPA to the same degree: the latter was more effective with respect to fT. DHEA-S responded much better to DXM than to EE-CPA. The basal level of SHBG was below the lower limit of the norm in 45% of the women. This indicates that hyperandrogenemia can be associated with normal and subnormal levels of SHBG. T and/or fT were elevated in all 40 women. DHEA-S was higher than normal in only 22 of the 40. DXM normalized the DHEA-S level in all but 1 case. In another 18 women, serum T and fT remained unaffected by DXM. This indicates an ovarian source of androgen excess in these cases. The number of cases was reduced from 18 to 4 when the OST was carried out. Even though DXM and EE-CPA are not completely organ-specific in action, the combination of both suppression tests seems to allow a higher degree of discrimination to be made between an ovarian and an adrenal component of hyperandrogenemia than is possible with either test alone.

Circulating sex hormone-binding globulin and testosterone in newborns and infants

The concentrations of sex hormone-binding globulin (SHBG) and testosterone (T) were measured in the cord blood of full-term newborns (14 boys, 15 girls) and pre-term newborns (10 boys, 5 girls), and in the venous circulation of 100 full-term infants aged 1-204 days. The ratio of T to SHBG (the 'free androgen index', FAI) was calculated to reflect the level of unbound T (the free, biologically active fraction). In boys' umbilical cord sera, T concentrations were significantly greater in arterial than in venous sera, while there was no such difference in the concentration of SHBG. Levels of SHBG in cord sera were considerably lower than those seen in the maternal circulation at term, but they were significantly greater in boys' than in girls' cord sera. Levels of T, and the FAI, were significantly greater in boys' arterial cord sera than in girls'. In early infancy, SHBG concentrations rose in both sexes, the highest values being seen in girls. In infant girls, levels of T and the FAI were constantly low. In infant boys, the expected peak in serum T concentrations was observed at 1-3 months the values approaching those seen in men. In contrast, values of the FAI at this age were relatively low, similar to those seen in women. This suggests that the elevation of male serum T during the first months of life lacks biological significance. However, it is important to realise that the FAI in male infants is about one order of magnitude larger than that in female infants at this time.

The diagnosis of polycystic ovaries in subfertile women

Laparoscopy was used to identify the polycystic ovary (PCO) in a group of subfertile women. A third were found to have PCO. These patients had higher levels of luteinizing hormone (LH), testosterone (T) and a higher free androgen index (FAI) than those with normal ovaries. Only 15% of patients with laparoscopic evidence of PCO were obese, hirsute and oligomenorrhoeic. Within the PCO group, hirsutism was strongly associated with obesity and a high FAI. A group of subfertile women with PCO and regular cycles was found who had no other identifiable cause for their infertility. These women had higher follicular phase concentrations of LH and higher FAI than ovulatory women with normal ovaries.

Hirsutism in the adolescent female

Prompt evaluation should be carried out for any adolescent complaining of excessive hair growth. The workup should be directed toward the exclusion of androgen secreting neoplasms and correctable adrenal pathology. A minimal workup must include total serum testosterone, DHEA-S, and prolactin. The clinician must then determine if further testing will alter management substantially. Treatment includes removal or neutralization of any discrete source of serum androgens, normalization of altered steroid physiology, and cosmetic correction (electrolysis) of existing hair growth. Successful management will allow normal socialization of the young woman afflicted with this distressing condition.

The role of chronic anovulation in the polycystic ovary syndrome: normalization of sex-hormone-binding globulin levels after clomiphene-induced ovulation

A group of anovulatory patients with polycystic ovaries (PCO) was given clomiphene citrate and compared with three control groups: normal women having spontaneous, ovulatory cycles, patients with PCO having spontaneous, regular, ovulatory cycles, and anovulatory patients without PCO. Comparisons were made at precise points of the menstrual cycle (taking the day of ovulation as day 0), using ultrasound estimates of mean follicular diameter, uterine volume, and endometrial thickness, and biochemical measurements of LH, FSH, oestradiol (E2), testosterone (T), progesterone (P) and sex-hormone-binding globulin (SHBG). Before clomiphene treatment, the anovulatory patients with PCO had significantly lower levels of SHBG and higher follicular phase concentrations of LH than all three control groups. After two cycles of clomiphene-induced ovulation, the serum LH concentration fell significantly and levels of SHBG increased significantly to levels similar to those found in spontaneously ovulating women with normal ovaries. It is likely that the loss of the usual considerable rise in E2 in both the follicular and luteal phases of ovulatory cycles is the main reason for the low SHBG found in the PCO syndrome. The loss of the normal P-induced gonadotrophin suppression may be a factor in allowing LH levels to rise.

Is the polycystic ovary a cause of infertility in the ovulatory woman?

Ovulatory women with polycystic ovaries (PCO) were compared with ovulatory women with normal ovaries, using high-resolution ultrasound and biochemical parameters to compare precise points in the menstrual cycle taking the day of ovulation as day 0. The PCO group had higher median follicular phase LH (days 'menses', -5, -3), FSH (days -5, -3) testosterone (days -3, -2) and free androgen index (days -5, -3, -1) than the controls. Women with PCO had a longer follicular phase and larger follicles. These results suggest that abnormal secretion of LH and free testosterone may contribute to the subfertility of women with PCO, possibly by premature activation of the oocyte or by interfering with folliculogenesis.

What are the ultrasound and biochemical features of impending ovulation?

Thirty-two ovulatory women had serial ultrasound measurements of uterine volume, endometrial thickness and leading follicular diameter compared with serum oestradiol, testosterone and sex-hormone binding globulin. Follicular diameter, endometrial thickness and uterine volume were significantly correlated with serum oestradiol. The day before ovulation was characterized by maximal values for oestradiol, testosterone, luteinizing hormone, endometrial thickness, uterine volume and leading follicular diameter. Leading follicular diameter and endometrial thickness in particular, appear to be useful parameters to indicate impending ovulation.

Which is the best test to detect the polycystic ovary?

Laparoscopy was used to characterize the ovaries of a group of infertile women. Patients with polycystic ovaries (PCO) were compared with those with normal ovaries. A free androgen index (FAI) greater than 4.5 was 100% specific and sensitive for detecting the PCO in a group of women with oligomenorrhoea. Overall, a biochemical 'screen' consisting of a luteinizing hormone (LH) level greater than 10 U/l, testosterone (T) greater 2.6 nmol/l, sex hormone binding globulin (SHBG) greater than 31 nmol/l or a FAI greater than 4.5 was 89% sensitive and 98% specific for PCO, which is comparable with the reliability of ultrasound for detecting the PCO.

Factors influencing the free androgen index in a group of subfertile women with normal ovaries

Eighty-five regularly cycling women with normal ovaries at laparoscopy, were studied to determine the factors that influence the free androgen index (FAI). It was found that body mass index (BMI), age of the patient and the phase of the menstrual cycle that the blood was collected can all affect the FAI. It is recommended that where possible, specimens should be collected in the early follicular phase to avoid misinterpretation of the result.

Elevated free androgen index as an indicator of polycystic ovaries in oligomenorrhoea without obesity or hirsuties

A group of oligomenorrhoeic women without obesity or hirsuties was investigated with high-resolution ultrasound, laparoscopy and biochemical parameters. In this series, polycystic ovaries (PCO), as defined by ultrasound and laparoscopy, are a common cause of oligomenorrhoea in women without the classic symptoms, and were strongly associated with an elevated free androgen index (FAI). Despite an elevated FAI, these women were not hirsute, It would seem reasonable to include a FAI in the investigation of the oligomenorrhoeic woman, along with the more 'standard' tests, such as thyroid function and a prolactin level.

The effect of season on the circulating concentrations of anterior pituitary, ovarian and adrenal cortex hormones and hormone binding proteins in the subarctic area; evidence of increased activity of the pituitary-ovarian axis in spring

To evaluate the effects of season on the function of the pituitary-ovarian axis and the adrenal cortex in a northern area with great seasonal variation in the length of daylight, 10 healthy women were investigated over 1 menstrual cycle in spring (May-June), autumn (August-September), early winter (November-December) and late winter (February-March). Serum concentrations of LH, FSH, prolactin, estradiol, progesterone, total and free testosterone, cortisol, sex hormone binding globulin (SHBG) and cortisol binding globulin (CBG) were measured, and the indices of free estradiol (FEI), free androgen (FAI) and free cortisol (FCI) were calculated on cycle days 3-4, 6-7, 10-11, on the presumed day of ovulation, and 6-7 and 9-10 days after the presumed ovulation. Spring was the season that most significantly differed from the other seasons. It was characterized by a significantly decreased concentration of SHBG and an increased FAI throughout the whole menstrual cycle, an increased FSH concentration during the follicular phase, significantly increased estradiol concentration and an increased FEI, and significantly decreased concentrations of FSH and LH during the luteal phase of the cycle. The concentration of cortisol and the FCI were significantly increased in the autumn compared with late winter, both seasons having similar day-length. The present data demonstrate that spring, with a long photoperiod, seems to be associated with increased pituitary-ovarian axis activity and androgenic activity, whereas adrenal cortex function did not show any association with day-length.

Changing concepts of active androgens in blood

We have provided a brief historical review of developments in our understanding of the endocrine mechanisms underlying the expression of androgen action in women. An alternative to the free hormone concept is considered which proposes that, at least in some target cells, androgens bound to SHBG are the biologically relevant molecules. In nearly every instance, the changes in blood levels of SHBG that have been observed are consistent with this idea. At present there are only bits of direct evidence to support the hypothetical mechanism proposed. As already mentioned, control of androgen action at the level of cellular uptake would provide obvious advantages as well as a potential mechanism to explain the antagonism between androgens and oestrogens which is still a mystery. It is important to note that the proposed mechanism is not obligatory for androgen or other steroid hormone action. Synthetic steroids which do not bind to SHBG or CBG clearly can gain access to target cells by simple diffusion and bind to intracellular receptors. Compounds such as methyltestosterone and dexamethasone are metabolized much more slowly than their natural counterparts and therefore are cleared slowly from the circulation. It is possible that the well-known difficulties in selecting appropriate therapeutic regimens with such compounds is related to the fact that they bypass an important regulatory step in steroid hormone action-modulated entry into target cells. Hopefully, the recent development of powerful new tools of molecular endocrinology will hasten the answer to the question: What is the active androgen in blood?

The adrenal cortex and virilization

The physiological control of adrenal androgen secretion has not been definitively established. However, there is evidence to suggest that a dexamethasone-suppressible factor other than ACTH may have a specific role to play. The majority of patients with idiopathic hirsutism (hirsutism associated with regular menstruation) have findings suggestive of adrenal androgen excess, including enhanced androgen responsiveness following administration of metyrapone, and respond to treatment with dexamethasone, 0.5 mg given each night. Patients with idiopathic hirsutism have elevated androgens but normal oestrogen and gonadotrophin levels. In contrast, while patients with polycystic ovary syndrome (PCOS) also demonstrate evidence of adrenal androgen excess, these patients have elevated oestrone levels and gonadotrophin secretion is abnormal. Approximately 50% of patients with PCOS treated with dexamethasone resume regular menstruation. Oestrone excess appears to be primary to the abnormal gonadotrophin secretion and to the development of PCOS. In non-obese patients with PCOS elevated oestrone appears to occur as a consequence of the availability of the excessive amounts of its immediate precursor, androstenedione, an androgen mainly of adrenal origin. Androstenedione is converted to oestrone in fat. Obese amenorrhoeic subjects have normal androstenedione values but elevated oestrone levels with abnormal gonadotrophin secretion as seen in PCOS. These findings indicate that abnormal gonadotrophin secretion is associated with elevated oestrone levels whether these occur as a consequence of excessive adrenal androgen secretion, or the excessive conversion of normal amounts of available androstenedione. Patients with idiopathic hirsutism and elevated androstenedione levels but normal oestrone values appeared to be protected against the development of PCOS by relatively poor conversion of androstenedione to oestrone. It is likely, therefore, that if patients with idiopathic hirsutism gain additional adipose tissue, elevated oestrone levels will result and PCOS will develop. These observations explain the frequent association of PCOS and obesity. There is a close clinical association between elevated androgen levels and hirsutism and between elevated oestrone levels and menstrual disturbances. However, some patients with amenorrhoea but without hirsutism may demonstrate marked elevations of androgens and oestrone, the correction of which leads to the resumption of regular ovulation. This presentation, 'amenorrhoea with cryptic hyperandrogenaemia', is probably explained by diminished sensitivity of androgen receptors.(ABSTRACT TRUNCATED AT 400 WORDS)