The contribution of SHBG to the variation in HOMA-IR is not dependent on endogenous oestrogen or androgen levels in postmenopausal women

Obesity and sexual health: focus on postmenopausal women

Menopause is a cardiometabolic transition with many women experiencing weight gain and redistribution of body fat. Hormonal changes may affect also several dimensions of well-being, including sexual function, with a high rate of female sexual dysfunction (FSD), which displays a multifactorial etiology. The most important biological factors range from chronic low-grade inflammation, associated with hypertrophic adipocytes that may translate into endothelial dysfunction and compromised blood flow through the genitourinary system, to insulin resistance and other neuroendocrine mechanisms targeting the sexual response. Psychosocial factors include poor body image, mood disorders, low self-esteem and life satisfaction, as well as partner's health and quality of relationship, and social stigma. Even unhealthy lifestyle, chronic conditions and putative weight-promoting medications may play a role. The aim of the present narrative review is to update and summarize the state of the art on the link between obesity and FSD in postmenopausal women, pointing to the paucity of high-quality studies and the need for further research with validated end points to assess both biomarkers of obesity and FSD. In addition, we provide general information on the diagnosis and treatment of FSD at menopause with a focus on dietary interventions, physical activity, anti-obesity drugs and bariatric surgery.

Testosterone and the heart: friend or foe?

Cardiovascular disease (CVD) is the leading cause of death in women aged 65 years and older. Sex hormones have been implicated as having a critical role in the evolution of CVD, with the focus mainly on estrogens in women. Available data also indicate that low testosterone blood levels may be detrimental to cardiovascular function in women. At blood concentrations considered normal for premenopausal women, testosterone has favorable effects on blood vessel function (relaxation and contraction), much of which is determined by the endothelial cells that line the inside of blood vessels. Testosterone enhances endothelium-dependent and independent brachial artery vasodilation and has an acute systolic blood pressure-lowering effect in postmenopausal women. Advantageous effects of testosterone in animal models have been seen for myocardial function and cardiac electrical signaling. Human data are mainly limited to observational and mechanistic studies, which mostly demonstrate beneficial effects of testosterone on cardiovascular health. Few studies of testosterone use in women, with cardiovascular endpoints as primary outcomes, have been published.

Prognostic value of insulin resistance in patients with female reproductive system malignancies: A multicenter cohort study

BACKGROUND

Insulin resistance (IR) and systemic inflammation are common in patients with cancer and are associated with poor prognosis. Few studies have reported IR in female reproductive system malignancies. This study investigated the prognostic value of IR and systemic inflammation in this population.

METHODS

A prospective multicenter real-world cohort study involving 571 patients diagnosed with female reproductive system malignancies was conducted. Lipid ratios (low-density lipoprotein-cholesterol/high-density lipoprotein-cholesterol [LHR], total cholesterol/HDL-cholesterol [TCHR], triglyceride/HDL-cholesterol [TGHR], fasting triglyceride/glucose [TyG]) were used to reflect IR. Optimal cut-off values were determined using maximally selected rank statistics. The Kaplan-Meier and Cox regression were used to calculate the hazard ratios for overall survival.

RESULTS

Over half (55.90%) of the 571 patients with female reproductive system malignancies (mean age: 52 years) had cervical cancer. Both IR and inflammation were negatively correlated with overall survival in female reproductive system cancer patients. Multivariate survival analysis showed that patients with high LHR (hazard ratio [HR]: 1.51, 95% confidence interval [CI]: 1.01-2.25, p = .046), high TCHR (HR: 1.90, 95% CI:1.22-2.95, p = .005), high TGHR (HR: 1.66, 95% CI:1.17-2.36, p = .004), high TyG (HR: 1.64, 95% CI:1.13-2.40, p = .010), high neutrophil lymphocyte ratio (NLR, HR: 2.03, 95% CI:1.44-2.86, p = .004) were significantly associated with worse prognosis. By calculating the concordance index of the four IR surrogate indicators, TyG was the most valuable indicator for the prognosis of patients with malignant tumors of the female reproductive system. High TyG combined with high NLR had improved prognostic value (HR: 3.22, 95% CI: 1.97-5.26, p < .001).

CONCLUSIONS

IR can be used as an independent predictor of prognosis in the female reproductive system malignancy population regardless of the IR substitution index. The combination of TyG and NLR could better predict the prognostic outcomes of women with breast cancer.

Estrone, sex hormone binding globulin and lipid profiles in older women: an observational study

OBJECTIVE

We investigated whether estrone and sex hormone binding globulin (SHBG) concentrations are associated with lipid concentrations in older postmenopausal women.

METHODS

This was a cross-sectional study of 6358 Australian women, aged 70-95 years, recruited between 2010 and 2014. Associations between estrone and SHBG and lipid concentrations were examined in participants not using medications that influence estrogen concentrations or lipid-lowering therapy. Linear regression models included age, body mass index, smoking, alcohol consumption, renal function and diabetes, with the lowest quartile (Q1) as the reference for estrone and SHBG.

RESULTS

The study included 3231 participants with median age of 74.0 (interquartile range 71.7-77.9) years. Estrone concentration Q3 and Q4 were positively associated with high-density lipoprotein cholesterol (HDL-C) (p = 0.017 and p = 0.046, respectively). Inverse associations were seen for estrone Q4 with total cholesterol (p = 0.018), Q2 and Q4 with non-HDL-C (p = 0.045 and p = 0.002, respectively) and Q3 and Q4 with triglycerides (p = 0.030 and p = 0.001, respectively). For SHBG, Q2, Q3 and Q4 were positively associated with HDL-C (all p < 0.001), and inversely with non-HDL-C (all p = 0.001) and triglycerides (all p < 0.001).

CONCLUSIONS

Estrone and SHBG are associated with lipid concentrations in older women. SHBG, but not estrone, may provide additional clinical predictive utility for the assessment of cardiometabolic disease risk in older women.

The cut-off value for HOMA-IR discriminating the insulin resistance based on the SHBG level in women with polycystic ovary syndrome

Introduction

The study aimed to estimate the cut-off value for homeostatic model assessment for insulin resistance (HOMA-IR) discriminating the insulin resistance based on the sex hormones binding globulin (SHBG) level in women with polycystic ovary syndrome (PCOS).

Materials and methods

Data from medical records of 854 Caucasian women diagnosed with PCOS were analyzed. Anthropometric data, fasting plasma glucose, insulin and SHBG levels were measured. HOMA-IR was calculated with a standard formula. The cut-off value was calculated using receiver-operating characteristics.

Results

Circulating SHBG levels below the normal range (26.1 nmol/L) were found in 25.4% of study participants. This subgroup had a significantly higher BMI, fasting glucose and insulin concentrations and HOMA-IR values. Empirical optimal cut-off values for HOMA-IR corresponding to low SHBG levels was ≥2.1 [area under the curve (AUC) 0.73, accuracy 0.65, sensitivity 72.3%, specificity 63.1%, positive predictive value (PPV) 40.0%, negative predictive value (NPV) 87.0%].

Conclusions

Our study suggests that the cut-off point for HOMA-IR discriminating the insulin resistance based on the SHBG level, in young Caucasian women with polycystic ovary syndrome is 2.1, and is consistent with the cut-off value adopted by the European Group for the Study of Insulin Resistance (above 2.0).

Examining the Role of Physical Activity Interventions in Modulating Androgens and Cardiovascular Health in Postmenopausal Women: A Narrative Review

A growing body of literature has examined the role of physical activity (PA) in modifying the effects of estrogen withdrawal on cardiovascular health in postmenopausal women, but the impact of PA on androgens is less clear. Changes in androgen concentrations following regular PA may improve cardiovascular health. This narrative review summarizes the literature assessing the impact of PA interventions on androgens in postmenopausal women. The association between changes in androgen concentrations and cardiovascular health following PA programs is also examined. Randomized controlled trials were included if they (i) implemented a PA program of any type and duration in postmenopausal women and (ii) measured changes in androgen concentrations. Following PA interventions, no changes in androstenedione, conflicting changes in dehydroepiandrosterone/dehydroepiandrosterone-sulfate, and increases in sex hormone-binding globulin concentrations were found. Total testosterone decreased following aerobic PA but increased after resistance training. Most aerobic PA interventions led to reductions in free testosterone. A combination of caloric restriction and/or fat loss enhanced the influence of PA on most androgens. Evidence exploring the relationship between changes in androgens and cardiovascular health indicators was scarce and inconsistent. PA has shown promise in modifying the concentrations of some androgens (free and total testosterone, sex hormone-binding globulin), and remains a well-known beneficial adjuvant option for postmenopausal women to manage their cardiovascular health. Fat loss influences the effect of PA on androgens, but the synergistic role of PA and androgens on cardiovascular health merits further examination. Many research gaps remain regarding the relationship between PA, androgens, and cardiovascular disease in postmenopausal women.

Associations between blood sex steroid concentrations and risk of major adverse cardiovascular events in healthy older women in Australia: a prospective cohort substudy of the ASPREE trial

BACKGROUND

Blood testosterone concentrations in women decline during the reproductive years and reach a nadir in the seventh decade, after which concentrations increase and are restored to those of reproductive-aged women early in the eighth decade. We aimed to establish the association between the concentration of testosterone in the blood and risk of major adverse cardiovascular events (MACE) and all-cause mortality in healthy older women.

METHODS

SHOW was a prospective cohort substudy of the longitudinal randomised ASPREE trial. Eligible participants were women aged at least 70 years from Australia with unimpaired cognition, no previous MACE, and a life expectancy of at least 5 years. Participants who were receiving hormonal or steroid therapy were ineligible for inclusion. We measured serum concentrations of sex steroids with liquid chromatography-tandem mass spectrometry and of SHBG with immunoassay. We compared lower concentrations of sex hormones with higher concentrations using four quartiles. Primary endpoints were risk of MACE and all-cause mortality, the associations of which with sex steroid concentrations were assessed using Cox proportional hazards regression that included age, body-mass index, smoking status, alcohol consumption, diabetes, hypertension, dyslipidaemia, impaired renal function, and treatment allocation in the ASPREE trial (aspirin vs placebo). ASPREE is registered with ClinicalTrials.gov, NCT01038583.

FINDINGS

Of the 9180 women recruited to the ASPREE trial between March 10, 2010, and Dec 31 2014, 6358 participants provided sufficient biobank samples at baseline and 5535 were included in the final analysis. Median age at entry was 74·0 years (IQR 71·7-77·7). During a median 4·4 years of follow-up (24 553 person-years), 144 (2·6%) women had a first MACE (incidence 5·9 per 1000 person-years). During a median 4·6 years of follow-up (3·8-5·6), 200 women died (7·9 per 1000 person-years). In the fully adjusted models, higher concentrations of testosterone were associated with a lower incidence of MACE (quartile 4 vs quartile 1: hazard ratio 0·57 [95% CI 0·36-0·91]; p=0·02), as were higher concentrations of DHEA (quartile 4 vs quartile 1: 0·61 [0·38-0·97]; p=0·04). For oestrone, a lower risk of MACE was seen for concentrations in quartile 2 only, compared with quartile 1 (0·55 [0·33-0·92]; p=0·02). In fully adjusted models, no association was seen between SHBG and MACE, or between any hormone or SHBG and all-cause mortality.

INTERPRETATION

Blood concentrations of testosterone and DHEA above the lowest quartile in older women were associated with a reduced risk of a first-ever MACE. Given that the physiological effects of DHEA are mediated through its steroid metabolites, if the current findings were to be replicated, trials investigating testosterone therapy for the primary prevention of ischaemic cardiovascular disease events in older women would be warranted.

FUNDING

The National Health and Medical Research Council of Australia, US National Institute on Aging, the Victorian Cancer Agency, the Commonwealth Scientific and Industrial Research Organisation, and Monash University.

Aquatic Exercise Positively Affects Physiological Frailty among Postmenopausal Women: A Randomized Controlled Clinical Trial

Frailty is a risk factor associated with aging. Physical exercise is an important lifestyle factor that can help to avoid risks associated with aging. Therefore, we aimed to determine the effects of aquatic exercise for 12 weeks on body composition, cardiovascular disease risk factors, insulin resistance, and aging-related sex hormones in elderly South Korean women. Twenty-two women aged 70–82 years were randomly assigned to groups that participated or did not participate (controls; n = 10 in aquatic exercise for 60 min, three times per week for 12 weeks (n = 12). Exercise intensity defined as the rating of perceived exertion (RPE), was increased from 12–13 to 13–14, and to 14–15 during weeks 1–4, 5–8, and 9–12, respectively. Body composition (skeletal muscle mass, ratio (%) body fat, and waist circumference), cardiovascular disease risk factors (total, high-density lipoprotein, and low-density lipoprotein cholesterol), insulin resistance (glucose, insulin, and homeostatic model assessment of insulin resistance [HOMA-IR]), and aging-related sex hormone changes (dehydroepiandrosterone-sulfate [DHEA-S]) and sex hormone-binding globulin [SHBG]) were assessed. Aquatic exercise safely improved body composition, reduced insulin resistance, and positively affected the sex hormones DHEA-S and SHBG as well as blood lipid profiles. Our findings suggested that the aquatic exercise program positively altered blood lipids, regulated glucose levels, and sex hormone levels. Therefore, regular, and continuous aquatic exercise is recommended to prevent frailty, decrease cardiovascular risk, and provide older women with an optimal quality of life as they age.

Use of Testosterone in Postmenopausal Women

The role of testosterone in women and its potential as a therapeutic agent continue to attract controversy. The clinical trials of testosterone therapy for women primarily have focused on treatment of female sexual dysfunction, with the largest placebo-controlled studies being of transdermal testosterone in postmenopausal women. Based on the cumulative data from these studies, loss of sexual desire with associated personal distress currently is the only agreed-on indication for judicious testosterone supplementation for postmenopausal women. This article reviews the physiology of testosterone in women, summarizes the findings from observational studies and clinical trials, and considers indications for testosterone use.

Associations between androgens and sexual function in premenopausal women: a cross-sectional study

BACKGROUND

Although clinicians often measure the serum concentration of androgens in premenopausal women presenting with sexual dysfunction, with some women given testosterone or dehydroepiandrosterone as treatment if their concentrations are low, whether androgens are determinants of sexual function in women of reproductive age is uncertain. We aimed to clarify the associations between androgens and sexual function in a community-based sample of non-health-care-seeking women.

METHODS

This is a substudy of the Grollo-Ruzzene cross-sectional study, which recruited women aged 18-39 years from eastern states in Australia (QLD, NSW, VIC). After providing consent, women completed an online survey that included the Profile of Female Secual Function (PFSF) questionnaire, and those who were who were not pregnant, breastfeeding, or using systemic steroids were asked to provide a blood sample. At sampling, women were asked the dates of their last menstrual bleed. Serum androgens was measured by liquid chromatography and tandem mass spectrometry and sex hormone binding globulin (SHBG) by immunoassay. Associations between androgens and domains of sexual function, assessed by the PFSF, were examined in participants with regular menstrual cycles. After univariable linear regression (model 1), age, BMI, stage of menstrual cycle, and smoking status were added to the model (model 2), and then parity, partner status, and psychotropic medication use (model 3).

FINDINGS

Of 6986 women who completed the online survey (surveys completed between Nov 11, 2016, and July 21, 2017), 3698 were eligible and 761 (20·6%) provided blood samples by Sept 30, 2017. Of those who provided a blood sample, 588 (77·3%) had regular menstrual cycles and were included in the analysis. Adjusting for age, BMI, cycle stage, smoking, parity, partner status, and psychoactive medication, sexual desire was positively associated with serum dehydroepiandrosterone (β-coefficient 3·39, 95% CI 0·65 to 6·03) and androstenedione (4·81, 0·16 to 9·12), and negatively with SHBG (-5.74, -9.54 to -1·90), each model explaining less than 4% of the variation in desire. Testosterone (6·00, 1·29 to 10·94) and androstenedione (6·05, 0·70 to 11·51) were significantly associated with orgasm, with the final models explaining less than 1% of the variation in orgasm. Significant associations were found between androstenedione (7·32, 0·93 to 13·08) and dehydroepiandrosterone (4·44, 0·86 to 7·95) and pleasure, and between testosterone and sexual self-image 5·87 (1·27 to 10·61), with inclusion of parity, partners status, and psychotropic drug use increasing the proportion of variation explained by each model to approximately 10%. There were no statistically significant associations between 11-oxygenated steroids and any PFSF domain, or between arousal or responsiveness and any hormone. No associations were seen between 11-oxygenated steroids and any sexual domain, or between arousal or responsiveness and any hormone.

INTERPRETATION

Associations between androgens and sexual function in premenopausal women are small, and their measurement offers no diagnostic use in this context. Further research to determine whether 11-ketoandrostenedione or 11-ketotestosterone are of clinical significance is warranted.

FUNDING

The Grollo-Ruzzene Foundation.

Longitudinal associations between sex hormone-binding globulin and insulin resistance

PURPOSE

We aimed to investigate the association between SHBG and the homeostatic model assessment of insulin resistance (HOMA-Ir) in men and women in a prospective observational study.

METHODS

The Vara-Skövde cohort is a random population of 2816 participants living in southwestern Sweden, aged 30-74. It was recruited between 2002 and 2005, and followed up in 2012-2014. After excluding participants on insulin therapy or hormone replacement therapy, 1193 individuals (649 men, 544 women) were included in the present study. Fasting blood samples were collected at both visits and stored in biobank. All participants were physically examined by a trained nurse. SHBG was measured with immunoassay technique. Linear regressions were computed to investigate the association between SHBG and HOMA-Ir both in cross-sectional and longitudinal analyses, adjusting for confounding factors.

RESULTS

The mean follow-up time was 9.7 ± 1.4 years. Concentrations of SHBG were significantly inversely associated with log transformed HOMA-Ir in all groups with estimated standardized slopes (95% CI): men: -0.20 (-0.3;-0.1), premenopausal women: -0.26 (-0.4;-0.2), postmenopausal women: -0.13 (-0.3;-0.0) at visit 1. At visit 2 the results were similar. When comparing the groups, a statistically significant difference was found between men and post-menopausal women (0.12 (0.0;0.2) P value = 0.04). In the fully adjusted model, SHBG at visit 1 was also associated with HOMA-Ir at visit 2, and the estimated slopes were -0.16 (-0.2;-0.1), -0.16 (-0.3;-0.1) and -0.07 (-0.2;0.0) for men, premenopausal and postmenopausal women, respectively.

MAIN CONCLUSION

Levels of SHBG predicted the development of insulin resistance in both men and women, regardless of menopausal state.

Testosterone and Estrone Increase From the Age of 70 Years: Findings From the Sex Hormones in Older Women Study

CONTEXT

There is a lack of understanding of what is normal in terms of sex steroid levels in older women.

OBJECTIVE

To determine whether sex steroid levels vary with age in and establish reference ranges for women >70 years of age.

DESIGN AND SETTING

Cross-sectional, community-based study.

PARTICIPANTS

Included 6392 women ≥70 years of age.

MAIN OUTCOME MEASURES

Sex steroids measured by liquid chromatography-tandem mass spectrometry. A reference group, to establish sex steroid age-specific reference ranges, excluded women using systemic or topical sex steroid, antiandrogen or glucocorticoid therapy, or an antiglycemic agent.

RESULTS

The reference group of 5326 women had a mean age of 75.1 (±4.2) years, range of 70 to 94.7 years. Median values (range) were 181.2 pmol/L (3.7 to 5768.9) for estrone (E1), 0.38 nmol/L (0.035 to 8.56) for testosterone (T), 2.60 nmol/L (0.07 to 46.85) for dehydroepiandrosterone (DHEA), and 41.6 nmol/L (2.4 to 176.6) for SHBG. Estradiol and DHT were below method sensitivity in 66.1% and 72.7% of the samples, respectively. Compared with women aged 70 to 74 years, women aged ≥85 years had higher median levels of E1 (11.7%, P = 0.01), T (11.3%, P = 0.02), and SHBG (22.7%, P < 0.001) and lower DHEA (30% less, P < 0.001). Women with overweight and obesity had higher E1 (P < 0.001) and T (P < 0.03) and lower SHBG (P < 0.001) than did women with normal body mass index. Smokers had 17.2% higher median T levels (P = 0.005).

CONCLUSION

From the age of 70 years, T and E1 increase with age, despite a steady decline in DHEA. Whether E1 and T are biomarkers for longevity or contribute to healthy aging merits investigation.

The Cut-off Values of Surrogate Measures for Insulin Sensitivity in a Healthy Population in Korea according to the Korean National Health and Nutrition Examination Survey (KNHANES) 2007-2010

BACKGROUND

This study aimed to identify the gender-specific characteristics of the surrogate measures of insulin resistance and to establish valid cut-off values for metabolic abnormalities in a representative sample in Korea.

METHODS

Data were collected from the datasets of the Korean National Health and Nutrition Examination Survey between 2007 and 2010. The total number of eligible participants was 10,997. We used three measures of insulin resistance: the homeostasis model assessment-insulin resistance (HOMA-IR), McAuley index, and triglyceride and glucose (TyG) index. The estimated cut-off values were determined using the highest score of the Youden index.

RESULTS

The area under the curve (AUC) of the HOMA-IR, McAuley index, and TyG index were 0.737 (95% confidence interval [CI], 0.725-0.750), 0.861 (95% CI, 0.853-0.870), and 0.877 (95% CI, 0.868-0.885), respectively. The cut-off values of the HOMA-IR were 2.20 in men, 2.55 in premenopausal women, and 2.03 in postmenopausal women, and those of the McAuley index were 6.4 in men and 6.6 in premenopausal and postmenopausal women. For the TyG index, the cut-off values were 4.76 in men and 4.71 in premenopausal and postmenopausal women.

CONCLUSION

In conclusion, the present study provides the valid cut-off values of the indirect surrogate measures of insulin sensitivity. These values may be used as reference for insulin sensitivity in a clinical setting and may provide a simple and supplementary method for identifying populations at risk of insulin resistance.

Androgens in postmenopausal women: a review

There is significant interest in the use of androgen therapy for postmenopausal women. This review provides background on endogenous androgens in women, describes factors that affect circulating androgen concentrations, and examines the relationship between low levels of androgens and sexual problems. Possible effects of androgens in postmenopausal women beyond sexual function also are discussed. Clinical trials of androgen therapy for the treatment of hypoactive sexual desire disorder are reviewed, with a discussion of potential risks. A practical approach to using androgens to treat low sexual desire with associated distress is presented, accompanied by an illustrative case.

Testosterone a key factor in gender related metabolic syndrome

Metabolic syndrome (MetS) is highly correlated with cardiovascular diseases. Although an excess of body fat is a determinant factor for MetS development, a reduced level of testosterone plays a fundamental role in its regulation. Low testosterone level is highly related to insulin resistance, visceral obesity and MetS. We have searched in Pubmed clinical trial with the password: testosterone and insulin resistance, and testosterone and MetS. We found 19 studies on the correlation between testosterone level with insulin resistance and 18 on the effect of testosterone therapy on MetS. A high correlation between low testosterone and insulin resistance has been found in men, but not in women. Testosterone administration in hypogonadal men improved MetS and reduced the mortality risk. Androgen and oestrogen receptors are expressed in adipocytes, muscle and liver tissue, and their activation is necessary to improve metabolic control. Normalization of testosterone level should be the primary treatment in men, along with caloric restriction and physical exercise. These findings come mainly from correlative data, and there remains a need for randomized trials to strengthen this evidence. This review will consider the effects of testosterone on the regulation and development of MetS in men and women.

Obesity in menopause - our negligence or an unfortunate inevitability?

Numerous concerns about menopause exist among women, and fear of an increase in body weight is one of the most important of them. This paper presents an overview of current knowledge concerning the etiology of obesity related to menopause and about the mechanisms of its development, with particular regard to the hormonal changes that occur during this period of life. The role of estrogens in the regulation of energy balance and the effect of sex hormones on metabolism of adipose tissue and other organs are presented. The consequence of the sharp decline in the secretion of estrogens with subsequent relative hyperandrogenemia is briefly discussed. The main intention of this review is to clarify what is inevitable and what perhaps results from negligence and unhealthy lifestyles. In the last part of the paper the possibilities of counteracting the progress of adverse changes in body composition, by promoting beneficial lifestyle modifications and the use of hormonal substitution treatment, in cases where it is reasonable and possible, are described.

Testosterone in women--the clinical significance

Testosterone is an essential hormone for women, with physiological actions mediated directly or via aromatisation to oestradiol throughout the body. Despite the crucial role of testosterone and the high circulating concentrations of this hormone relative to oestradiol in women, studies of its action and the effects of testosterone deficiency and replacement in women are scarce. The primary indication for the prescription of testosterone for women is loss of sexual desire, which causes affected women substantial concern. That no formulation has been approved for this purpose has not impeded the widespread use of testosterone by women--either off-label or as compounded therapy. Observational studies indicate that testosterone has favourable cardiovascular effects measured by surrogate outcomes; however, associations between endogenous testosterone and the risk of cardiovascular disease and total mortality, particularly in older women, are yet to be established. Adverse cardiovascular effects have not been seen in studies of transdermal testosterone therapy in women. Clinical trials suggest that exogenous testosterone enhances cognitive performance and improves musculoskeletal health in postmenopausal women. Unmet needs include the availability of approved testosterone formulations for women and studies to elucidate the contribution of testosterone to cardiovascular, cognitive, and musculoskeletal health and the risk of cancer.

Metabolic Syndrome and Menopause: Pathophysiology, Clinical and Diagnostic Significance

Menopause is a risk factor for cardiometabolic diseases, including metabolic syndrome (MetS), type 2 diabetes, and cardiovascular diseases. MetS is a constellation of interdependent factors such as insulin resistance, abdominal obesity, dyslipidemia, and hypertension. The prevalence of MetS in postmenopause is due to loss of the protective role of estrogens and increased circulating androgens resulting in changes to body fat distribution and development of abdominal obesity. Excessive visceral adipose tissue plays an important role due to synthesis and secretion of bioactive substances such as adipocytokines, proinflammatory cytokines, reactive oxygen species, prothrombotic, and vasoconstrictor factors. MetS may also impact risk assessment of breast cancer, osteoporosis and chronic kidney disease, and quality of life during the menopausal transition. Increased MetS has stimulated the exploration of new laboratory tests for early detection and therapies.

Prevention of diseases after menopause

Women may expect to spend more than a third of their lives after menopause. Beginning in the sixth decade, many chronic diseases will begin to emerge, which will affect both the quality and quantity of a woman's life. Thus, the onset of menopause heralds an opportunity for prevention strategies to improve the quality of life and enhance longevity. Obesity, metabolic syndrome and diabetes, cardiovascular disease, osteoporosis and osteoarthritis, cognitive decline, dementia and depression, and cancer are the major diseases of concern. Prevention strategies at menopause have to begin with screening and careful assessment for risk factors, which should also include molecular and genetic diagnostics, as these become available. Identification of certain risks will then allow directed therapy. Evidence-based prevention for the diseases noted above include lifestyle management, cessation of smoking, curtailing excessive alcohol consumption, a healthy diet and moderate exercise, as well as mentally stimulating activities. Although the most recent publications from the follow-up studies of the Women's Health Initiative do not recommend menopause hormonal therapy as a prevention strategy, these conclusions may not be fully valid for midlife women, on the basis of the existing data. For healthy women aged 50-59 years, estrogen therapy decreases coronary heart disease and all-cause mortality; this interpretation is entirely consistent with results from other randomized, controlled trials and observational studies. Thus. as part of a comprehensive strategy to prevent chronic disease after menopause, menopausal hormone therapy, particularly estrogen therapy may be considered as part of the armamentarium.

Immunologic and mass-spectrometric estimates of SHBG concentrations in healthy women

OBJECTIVE

Sex-hormone binding globulin (SHBG) concentrations across the adult female lifespan are not well defined. To address this knowledge gap, SHBG was quantified by both immunological and criterion methods, viz, mass spectrometry (MS).

SETTING

Center for Translational Science Activities (CTSA).

PARTICIPANTS

Healthy nonpregnant women (N=120) ages 21 to 79 years.

OUTCOMES

SHBG, testosterone (T), estradiol (E2) and estrone (E1) each determined by MS. Uni- and multivariate regression of SHBG concentrations on age, body mass index (BMI), total and visceral abdominal fat (TAF, AVF), albumin, glucose, insulin, sex steroids, selected cytokines, blood pressure, and lipids.

RESULTS

By univariate regression, MS-estimated SHBG correlated negatively with BMI, TAF, AVF, insulin, free T and bioavailable T (bio T) (each P≤10(-4)), but not with blood pressure or lipids. By stepwise multivariate regression analysis, free and total T (both positive) and bio T (negative) were correlated with SHBG in all 4 assays (each P<10(-15), R(2)≥0.481). In addition, TAF and BMI were negatively associated with SHBG (P≤0.0066) in 2 SHBG assays, and estrone and IL-8 with SHBG weakly (P≤0.035) in one SHBG assay each. When nonsignificant cytokines were excluded, SHBG was jointly associated with AVF, total T and HDL (P<10(-9), R(2)=0.358).

CONCLUSION

According to MS, three metabolic factors, T, AVF and HDL, together explain more than one-third of the interindividual variation in SHBG levels. We speculate that these measures reflect insulin action.

Estrogen: a master regulator of bioenergetic systems in the brain and body

Estrogen is a fundamental regulator of the metabolic system of the female brain and body. Within the brain, estrogen regulates glucose transport, aerobic glycolysis, and mitochondrial function to generate ATP. In the body, estrogen protects against adiposity, insulin resistance, and type II diabetes, and regulates energy intake and expenditure. During menopause, decline in circulating estrogen is coincident with decline in brain bioenergetics and shift towards a metabolically compromised phenotype. Compensatory bioenergetic adaptations, or lack thereof, to estrogen loss could determine risk of late-onset Alzheimer's disease. Estrogen coordinates brain and body metabolism, such that peripheral metabolic state can indicate bioenergetic status of the brain. By generating biomarker profiles that encompass peripheral metabolic changes occurring with menopause, individual risk profiles for decreased brain bioenergetics and cognitive decline can be created. Biomarker profiles could identify women at risk while also serving as indicators of efficacy of hormone therapy or other preventative interventions.

Sex hormone binding globulin and insulin resistance

Sex hormone binding globulin (SHBG) is a glycoprotein composed of two 373-amino-acid subunits. The SHBG gene and a promotor region have been identified. The SHBG receptor has yet to be cloned but is known to act through a G-protein-linked second-messenger system following plasma membrane binding. The principal function of SHBG has traditionally been considered to be that of a transport protein for sex steroids, regulating circulating concentrations of free (unbound) hormones and their transport to target tissues. Recent research suggests that SHBG has functions in addition to the binding and transport of sex steroids. Observational studies have associated a low SHBG concentration with an increased incidence of type 2 diabetes mellitus (DM) independent of sex hormone levels in men and women. Genetic studies using Mendelian randomization analysis linking three single nucleotide polymorphisms of the SHBG gene to risk of developing type 2 DM suggest SHBG may have a role in the pathogenesis of type 2 DM. The correlation between SHBG and insulin resistance that is evident in a number of cross-sectional studies is in keeping with the suggestion that the association between SHBG and incidence of type 2 DM is explained by insulin resistance. Several potential mechanisms may account for this association, including the identification of dietary factors that influence SHBG gene transcription. Further research to characterize the SHBG-receptor and the SHBG second messenger system is required. An interventional study examining the effects on insulin resistance of altering SHBG concentrations may help in determining whether this association is causal.

Associations of estrogen and testosterone with insulin resistance in pre- and postmenopausal women with and without hormone therapy

BACKGROUND

Estrogen deficiency due to natural menopause or surgical menopause has been suggested to have an adverse effect on insulin resistance. Testosterone and sex hormone-binding globulin (SHBG) as well as estrogen are also associated with insulin resistance in women. However, to date, the associations of estradiol, testosterone and SHBG with insulin resistance according to estrogen level have not been clarified.

OBJECTIVES

We examined the associations of estradiol, testosterone and SHBG with insulin resistance in pre- and in postmenopausal women and postmenopausal women who had received hormone therapy to clarify whether the associations differ depending on the estrogen status.

PATIENTS AND METHODS

Twenty premenopausal women and thirty-two postmenopausal women were enrolled in this study. Fifteen postmenopausal women received oral conjugated equine estrogen (CEE) (0.625 mg) everyday for 12 months. Serum levels of estradiol, testosterone, SHBG and insulin and plasma levels of glucose were measured.

RESULTS

Serum estradiol levels tended to have a negative correlation with homeostasis model assessment of insulin resistance (HOMA-IR) in premenopausal women but not in postmenopausal women. On the other hand, free testosterone levels tended to have a positive correlation with HOMA-IR in postmenopausal women but not in premenopausal women. Serum SHBG levels showed significant negative correlations with HOMA-IR in both pre- and postmenopausal women. SHBG level was significantly increased, free testosterone level was significantly decreased and HOMA-IR was significantly decreased at 12 months after CEE administration. However, there were no significant correlations of changes between estradiol, SHBG or free testosterone and HOMA-IR.

CONCLUSIONS

The associations of sex steroid hormones with insulin resistance are different depending on the estrogen status.