Relationship between sex hormone-binding globulin levels and features of the metabolic syndrome

Androgenicity in Young Women and Development of Metabolic Syndrome Before Menopause: The CARDIA and CARDIA Women's Studies

Context

There are no reported data from prospective long-term studies on the relation of androgen levels in young women with development of metabolic syndrome (MetS) before menopause.

Objective

We investigated associations of androgens and SHBG with incident MetS during 23 years of follow-up.

Methods

We included 366 White and 375 Black women ages 20 to 32 years participating in the CARDIA study and CARDIA Women's study, free of MetS at baseline examination (1987-1988), and premenopausal 23 years later. Androgens and SHBG were categorized into quartiles. MetS was defined according to the American Heart Association/National Heart, Lung, and Blood Institute 2009 Joint Scientific Statement. Cox proportional hazards models were used.

Results

By year 23, 30% of women developed MetS. Adjusting for baseline age, race, and education, hazard ratios (95% CI) of developing MetS were 1.46 (1.02-2.10) and 2.22 (1.53-3.21) for women in the highest vs lowest total testosterone (T) and free T quartile, respectively. The hazards of developing MetS were 47%, 59%, and 53% lower for women with SHBG in the second, third, and fourth quartiles (vs lowest quartile), respectively. Associations were attenuated for total T with further adjustments for smoking, physical activity, menstrual status, oral contraceptive/hormone (OCHM) use, insulin level, oligomenorrhea, and age at menarche, but remained statistically significant for free T and SHBG. Associations were similar for both Blacks and Whites, and OCHM nonusers, but not for OCHM users.

Conclusion

High androgenicity in young premenopausal women is associated with higher risk of future MetS, suggesting that early assessment of androgens may contribute to prevention.

Interaction between gut microbiota and sex hormones and their relation to sexual dimorphism in metabolic diseases

Metabolic diseases, such as obesity, metabolic syndrome (MetS) and type 2 diabetes (T2D), are now a widespread pandemic in the developed world. These pathologies show sex differences in their development and prevalence, and sex steroids, mainly estrogen and testosterone, are thought to play a prominent role in this sexual dimorphism. The influence of sex hormones on these pathologies is not only reflected in differences between men and women, but also between women themselves, depending on the hormonal changes associated with the menopause. The observed sex differences in gut microbiota composition have led to multiple studies highlighting the interaction between steroid hormones and the gut microbiota and its influence on metabolic diseases, ultimately pointing to a new therapy for these diseases based on the manipulation of the gut microbiota. This review aims to shed light on the role of sexual hormones in sex differences in the development and prevalence of metabolic diseases, focusing on obesity, MetS and T2D. We focus also the interaction between sex hormones and the gut microbiota, and in particular the role of microbiota in aspects such as gut barrier integrity, inflammatory status, and the gut-brain axis, given the relevance of these factors in the development of metabolic diseases.

The brown bear as a translational model for sedentary lifestyle-related diseases

Sedentary lifestyle accelerates biological ageing, is a major risk factor for developing metabolic syndrome and is associated with cardiovascular disease, diabetes mellitus, kidney failure, sarcopenia and osteoporosis. In contrast to the linear path to worsening health in humans with metabolic syndrome, brown bears have developed a circular metabolic plasticity enabling these animals to tolerate obesity and a 'sedentary lifestyle' during hibernation and exit the den metabolically healthy in spring. Bears are close to humans physiology wise, much closer than rodents, the preferred experimental animals in medical research, and may better serve as translational model to develop treatments for lifestyle-related diseases. In this review, aspects of brown bear hibernation survival strategies are outlined and conceivable experimental strategies to learn from bears are described.

Nutritional status and follicular-derived thyroid cancer: An update

The incidence of differentiated thyroid cancer has been increasing in the last decades all over the world. Such a steady growth cannot be entirely attributable to more intensive thyroid nodule screening and more sensitive diagnostic procedures. Several environmental factors have changed with sufficient rapidity in the same time frame and may represent credible candidates for this increase. They include modified iodine intake, lifestyle-associated risk factors, exposure to various toxic compounds, pollutants and xenobiotics, nutritional deficiencies, eating habits and comorbidities. Foremost, nutritional patterns have gained high interest as possible promoters and modifiable risk factors for thyroid cancer in recent years. The aim of this narrative review is to focus on the relationship between thyroid cancer and nutritional factors, dietary habits and obesity. Low iodine intake has been associated to increased risk of thyroid cancer, favoring the development of more aggressive histotypes. Moreover, correction of iodine deficiency can shift thyroid cancer subtypes toward less aggressive forms, without affecting the overall risk for cancer. Actually, evidence regarding the association between selenium and vitamin D deficiency and thyroid cancer is very limited, despite their well-known anti-cancer potentials, and the clinical usefulness of their supplementation is still uncertain in this setting. Albeit the relationship between single foods and thyroid cancer is difficult to examine, fish and iodine-rich foods, vegetables, and fruits might exert protective effects on thyroid cancer risk. Conversely, no clear association has been found for other foods to date. Lastly, a clear association between obesity and the risk of thyroid cancer, with more aggressive behavior, seems to emerge from most studies, likely involving variations in thyroid function and chronic inflammation mediated by cytokines, insulin, leptin and adiponectins. Although no definite association between dietary factors and thyroid cancer has been firmly established so far, some nutritional patterns, together with excessive weight, seem to play a relevant role in thyroid cancer carcinogenesis as well as in its severity and aggressiveness. These effects may play an additive role to the well-established one exerted by environmental carcinogens, such as pollutants and radiation exposure.

The relationship between components of metabolic syndrome and plasma level of sex hormone-binding globulin

Plasma concentration of sex hormone-binding globulin (SHBG), as an androgen binding protein, is impressed by many physiological and environmental factors. Recent studies have shown that plasma level of SHBG is related to some components of metabolic syndrome (MetS); however, in contrast, few articles failed to show any associations between SHBG and MetS. So, this study was conducted to investigate the relationship between Components of Metabolic Syndrome and Plasma Level of Sex Hormone-Binding Globulin. In this study, after measuring the plasma level of SHBG in 84 individuals, the relation between MetS and the plasma level of SHBG was investigated. After evaluating the plasma level of SHBG and metabolic abnormalities in men and women, we investigated the factors which mentioned above in two groups including patients with and without MetS. Also, the metabolic abnormalities which evaluated in this study including plasma level of 25-hydroxyvitamin D, serum uric acid (SUA), Albumin, lipid profiles and etc. according to five components of MetS. Our result shows that SHBG could contributed to some laboratory parameters such as LDL-C (P<0.05), total cholesterol (P<0.05), triglycerides (P<0.05) and etc. in men, but not in women. On the other hand, we observed that concentration of SHBG is higher in patients with MetS (P<0.05); however, results from our experiment showed that there is no relation between lower level of SHBG and five components of MetS such as central obesity, raised fasting plasma glucose (FPG) (P>0.05), reduced HDL-C (P>0.05), raised triglycerides (P>0.05) and raised blood pressure (P>0.05) in both men and women. There is a significant association between SHBG and Log-Hip Circumference (P<0.05), Non-HDL-C (P<0.05) and Log-25(OH)D (P<0.05) was seen in this cross-section study in both men and women. Results obtained from our study suggest that SHBG is not a powerful enough factor to use as a predictor of MetS alone and there is no association between plasma level of SHBG and development of five components of MetS, however, lower SHBG level may contributed to lipid profiles.

Sex Hormone Levels - Estradiol, Testosterone, and Sex Hormone Binding Globulin as a Risk Marker for Atherosclerotic Coronary Artery Disease in Post-menopausal Women

CONTEXT

Sex hormones levels determine the risk of occurrence of coronary artery disease (CAD) in post-menopausal (PM) women.

AIMS

To investigate the relationship between sex hormones (estradiol and testosterone)/sex hormone binding globulin (SHBG) and cardiovascular risk factors in PM women. In addition, we learned the association between these sex hormones/SHBG and the occurrence of atherosclerotic CAD event in PM women.

SETTINGS AND DESIGN

Cross-sectional case- control study.

SUBJECTS AND METHODS

Subjects recruited in the present study were from the cardiology outpatient clinic or Emergency department Guwahati Medical College and Hospital, Assam. The subjects were grouped into two categories after appropriate exclusion criteria: Cases - PM women with documented CAD (n = 40) and controls - Healthy PM women (n = 30). The medical history, clinical examination, and investigations including serum estradiol, total testosterone, SHBG, free testosterone index (FTI), high-sensitivity C-reactive protein (hs-CRP), lipid profile, carotid intima-media thickness (CIMT), fasting plasma glucose (FPG), and postprandial plasma glucose (PPPG) were done and analyzed.

STATISTICAL ANALYSIS USED

Pearson correlation between sex hormones and CAD risk factors was done. The association between sex hormones and CAD risk factors among PM women was analyzed by multiple logistic regression. The statistical significance was set at the 0.05 level.

RESULTS

The mean age of all the subjects was 62.27 ± 6.9 years. Among the cases, a significant positive correlation was found between total testosterone/FTI and waist circumference, W/H ratio, triglyceride levels, hs-CRP, and CIMT (P < 0.01). In addition, a significant negative correlation was found between total testosterone and FTI with high-density lipoprotein-cholesterol levels (P < 0.01). The multiple logistic regression analysis showed that total testosterone levels (P < 0.01) and SHBG (P < 0.01) are independently associated with the occurrence of atherosclerotic CAD in PM.

CONCLUSION

We conclude that increased serum testosterone levels and low SHBG in PM women are associated with the development of atherosclerotic cardiovascular risk factors.

Can Low SHBG Serum Concentration Be A Good Early Marker Of Male Hypogonadism In Metabolic Syndrome?

INTRODUCTION

In men suffering from metabolic syndrome, accompanying insulin resistance may result in a lowering of sex hormone-binding globulin (SHBG) plasma levels and cause changes in their androgenic status.

AIM

The objective of the research was to assess selected androgens and SHBG plasma levels in males meeting diagnostic criteria for MS compared to healthy males.

PATIENTS AND METHODS

The group consisted of 65 men aged between 40 and 70 years old fitting IDF metabolic syndrome criteria and 84 controls. Dehydroepiandrosterone (DHEA) and its sulphate (DHEA-S), total and free testosterone and SHBG serum levels were evaluated. Calculated free and bioavailable testosterone were estimated using an algorithm proposed by the International Society for the Study of the Aging Male.

RESULTS

Men diagnosed with MS showed a statistically significant decrease in plasma levels of DHEA in comparison to healthy ones: 11.579 (8.39-15.56) vs 14.014 (9.611-17.125) ng/mL; p = 0.0350, SHBG: 47.46 (35.78-62.83) vs 71.965 (54.45-91.56) nM/L; p<0.0001 and total testosterone: 5.2 (3.8-6.5) vs 6.3 (5.4-8.25) ng/mL; p = 0.0001 (values presented as a median with Q1-Q3).

CONCLUSION

The results suggest that SHBG is a good early marker for metabolic dysregulation in MS, considering its strength of association and significance is comparable to, or better than, those of MS criteria.

Is serum sex hormone-binding globulin a dominant risk factor for metabolic syndrome?

This multi-center, cross-sectional study investigated the association between serum testosterone (T) levels, serum sex hormone-binding globulin (SHBG) levels, and the risk of metabolic syndrome (MS) in 3332 adult Chinese men. The prevalence of MS was 34.7%, and men with MS had lower serum levels of total T (TT) and SHBG than those without MS (P < 0.001). There was no significant difference in serum free T (FT) levels between subjects with and without MS (P = 0.627). In logistic regression analysis, the association between MS and serum SHBG levels persisted after adjusting for age, body mass index (BMI), smoking and drinking status, and serum TT (odds ratio [OR] 0.962, 95% confidence interval [95% CI] 0.954-0.969, P< 0.01). However, the association between serum TT level and the risk of MS was weak after adjusting for age, BMI, SHBG level, and smoking and drinking status (OR 0.981, 95% CI 0.960-1.007). Our study reveals that both serum TT and SHBG levels, but not serum FT, are inversely associated with the prevalence of MS and that serum SHBG is an independent and dominant risk factor for MS.

Obesity-related endometrial cancer: an update on survivorship approaches to reducing cardiovascular death

As the rate of obesity increases worldwide, so will the number of women diagnosed with obesity-related malignancy. The strongest correlation between obesity and cancer is endometrial cancer (EC). Obesity is the most significant modifiable risk factor for development of EC and also contributes to the most common cause of death in EC survivors-cardiovascular disease (CVD). Most cancer survivors after diagnosis do not implement lifestyle changes aimed at weight-loss and CVD risk reduction. This selective review highlights recent novel and unique approaches for managing CVD co-morbidities in EC survivorship.

Gender-specific associations of serum sex hormone-binding globulin with features of metabolic syndrome in children

BACKGROUND

Sex hormone-binding globulin (SHBG) has been proposed as a biomarker of MetS in children and adults. We aim to determine the associations of SHBG with components of MetS in children from the Middle-East where the prevalence of MetS are on the rise.

METHODS

In this cross-sectional study, a total of 509 randomly selected school children (226 boys and 283 girls) aged 12-16 years were recruited. Fasting blood glucose and lipid profile were determined using routine laboratory procedures. Serum SHBG is measured with Cobas e411 using an electrochemiluminescence immunoassay. The modified definition of ATP-III (NHANES III) was used for the diagnosis of MetS.

RESULTS

Among 509 children, 23.4 % had metabolic syndrome. Boys had a significantly higher waist circumference and systolic blood pressure (p < 0.032, 0.024, respectively) than girls, while levels of glucose (p < 0.029), and SHBG (p < 0.003) were significantly higher in girls than in boys. In overall population, a significant inverse correlation of SHBG level with age, BMI, systolic blood pressure and triglycerides and a significant direct correlation between SHBG level and HDL-c was exhibited. Children with the lowest tertile of serum SHBG had significantly higher prevalence of MetS (p < 0.05). ROC curve shows SHBG level as more sensitive marker of MetS in boys (AUC = 0.70, p < 0.001).

CONCLUSIONS

Serum SHBG is significantly more sensitive in identifying MetS in boys, not girls, indicating gender dimorphism.

Metabolic syndrome is associated with increased breast cancer risk: a systematic review with meta-analysis

Background. Although individual metabolic risk factors are reported to be associated with breast cancer risk, controversy surrounds risk of breast cancer from metabolic syndrome (MS). We report the first systematic review and meta-analysis of the association between MS and breast cancer risk in all adult females. Methods. Studies were retrieved by searching four electronic reference databases [PubMed, Cumulative Index to Nursing and Allied Health Literature (CINAHL), Web of Science, and ProQuest through June 30, 2012] and cross-referencing retrieved articles. Eligible for inclusion were longitudinal studies reporting associations between MS and breast cancer risk among females aged 18 years and older. Relative risks and 95% confidence intervals were calculated for each study and pooled using random-effects models. Publication bias was assessed quantitatively (Trim and Fill) and qualitatively (funnel plots). Heterogeneity was examined using Q and I² statistics. Results. Representing nine independent cohorts and 97,277 adult females, eight studies met the inclusion criteria. A modest, positive association was observed between MS and breast cancer risk (RR: 1.47, 95% CI, 1.15–1.87; z = 3.13; p = 0.002; Q = 26.28, p = 0.001; I² = 69.55%). No publication bias was observed. Conclusions. MS is associated with increased breast cancer risk in adult women.

Plasma non-esterified fatty acid levels in children and their relationship with sex steroids

OBJECTIVE

Puberty is associated with decreased insulin sensitivity. Sexual hormones have been related with the onset of insulin resistance, but their relationship with non-esterified fatty acids (NEFA) remains unexplored. The aim of this study was to evaluate circulating NEFA levels in population-based samples of prepubertal children and adolescents and to analyze the association of NEFA with obesity, insulin resistance, and sexual hormones in adolescents.

EXPERIMENTAL

The studied population included 854 randomly selected 6-8-year-old children and 822 children aged 12-16years. NEFA levels were determined using a commercial kit. Testosterone and estradiol levels were determined by RIA, and insulin and sex hormone binding protein by IRMA. HOMA was calculated as an indicator of insulin resistance.

RESULTS

NEFA levels were lower in adolescents than in 6-8-year-old children, and decreased progressively with age between 12-year-olds and 16-year-olds. No significant differences in NEFA levels were observed between obese and non-obese adolescents. NEFA were not correlated with insulin or HOMA in 12-16-year-old girls, and appear negatively correlated with these variables in boys. Insulin and HOMA were negatively correlated with SHBG levels in both sexes adjusting by age but NEFA levels were not.

CONCLUSIONS

NEFA levels decrease with age in adolescents and are not significantly increased in obese children, supporting the fact that the decreased insulin sensitivity at this age is not affecting NEFA metabolism. Although SHBG is related to insulin and HOMA independently of age in both sexes, SHBG levels are not associated with NEFA.

Endocrinology of menopause

Menopause is a natural process that occurs in women's lives as part of normal aging. Many women go through the menopausal transition with few or no symptoms, while some have significant, or even disabling, symptoms. This manuscript reviews the physiologic processes and symptoms connected with menopause and the diseases associated with menopause, as well as how menopausal symptoms are managed.

Sex hormone-binding globulin and the risk for metabolic syndrome in children of South Asian Indian origin

OBJECTIVE

To determine whether the plasma level of sex hormone-binding globulin (SHBG) identifies South Asian Indian children at risk for metabolic syndrome.

METHODS

Adults and their children aged 5 to 9 years were recruited at the annual health fair at the Hindu temple serving the South Asian Indian community in Louisville, Kentucky. Anthropometric data were collected in adults and children, and blood pressure, lipid, and glucose levels were measured in adults. SHBG levels were measured in children using a fingerstick blood sample. In adults, metabolic syndrome was diagnosed according to the International Diabetes Federation criteria. Twelve months later, follow-up anthropometric data were obtained for a portion of the children.

RESULTS

The study included 30 sets of parents and 30 children. The prevalence of metabolic syndrome among 310 adults attending the health fair was 42% in men and 39% in women. Children with 1 parent with metabolic syndrome had 24% lower SHBG levels that increased to 55% if both parents had metabolic syndrome. SHBG levels were inversely related to waist circumference and to body mass index percentile. Both SHBG and waist circumference predicted weight gain over 1 year in children. CONCLUSIONS Low SHBG levels were found in South Asian Indian children whose parents had attributes of metabolic syndrome. The dose dependency of SHBG is consistent with inheritance of a genetic trait, and if the results are applicable to other racial/ethnic groups, SHBG may be a useful marker to identify at-risk children for early intervention.

The relationship between endogenous androgens and body fat distribution in early and late postmenopausal women

Objectives

To investigate the relationship between endogenous androgens and body fat distribution in early and late postmenopausal women.

Materials and Methods

We enrolled postmenopausal women consisting of an early group (≤5 years since menopause, n = 105) and a late group (≥10 years since menopause, n = 107). Each group was subdivided into normal weight (BMI <24 kg/m²) group, overweight and obese (BMI ≥24 kg/m²) group. Fasting total testosterone (T), dehydroepiandrosterone-sulfate (DHEA-S) and sex hormone-binding globulin (SHBG) levels were measured. Body fat distribution was evaluated by dual-energy X-ray absorptiometry (DEXA).

Results

Late postmenopausal women had a higher proportion of body fat than early postmenopausal women. The body fat of the overweight and obese women had a greater tendency to accumulate in the abdomen compared with the normal weight women both in early and late postmenopausal groups. The overweight and obese women had a higher free testosterone (FT) than the normal weight women in early postmenopausal women (P<0.05). In late postmenopausal women, the overweight and obese women had higher DHEA-S levels than normal weight women (P<0.05). No direct relationship was observed between the T levels and body fat distribution both in early and late postmenopausal groups (P>0.05).The FT in early postmenopausal women and the DHEA-S levels in late postmenopausal women correlated positively with the trunk/leg fat ratio (T/L) and the proportion of android fat whereas correlated negatively with the proportion of gynoid fat in the partial correlation and multiple linear regression analyses (all P<0.05).

Conclusions

Serum T levels do not correlate directly with body fat distribution, the FT in early postmenopausal women and DHEA-S levels in late postmenopausal women correlate positively with abdominal fat accumulation.

Association between sex hormone levels and abnormal metabolism in a population of elderly Chinese men

OBJECTIVE

Low testosterone levels may be a signal of poor health. This study aimed to investigate the effects of age and abnormal metabolism on sex hormones in Chinese male.

METHODS

Three hundred and thirty-seven elder men were enrolled into this single-center, cross-sectional study, and their sex hormone levels and metabolic parameters were assessed.

RESULTS

Serum follicle-stimulating hormone (FSH), luteinizing hormone (LH) and sex-hormone-binding globulin (SHBG) concentrations increased with age, while free testosterone index (FTI), testosterone secretion index (TSI), estradiol (E2)/SHBG and progestin (PROG) decreased. Abnormal metabolisms were related to androgen indices (TT, FT, BT, FTI, TSI, T/E2), SHBG and E2/SHBG even after adjusting by age and macrovascular disease. Obesity and overweight, hyperglycemia and dyslipidemia were the most important abnormal metabolism that related to decreased androgen indices. Including SHBG in the stepwise regression increased the explanation effect of TT and BT by 32.7% and 28.5%, respectively, and all metabolic indices were excluded. Abnormal metabolism indies (BMI and PBG) were correlated to the decrease in SHBG levels, while age and LH was positively correlated to SHBG levels.

CONCLUSIONS

Age and abnormal metabolism were independently important factors associated with the sex hormone levels in elderly Chinese men, which were all mediated by SHBG.

Pathophysiology of human visceral obesity: an update

Excess intra-abdominal adipose tissue accumulation, often termed visceral obesity, is part of a phenotype including dysfunctional subcutaneous adipose tissue expansion and ectopic triglyceride storage closely related to clustering cardiometabolic risk factors. Hypertriglyceridemia; increased free fatty acid availability; adipose tissue release of proinflammatory cytokines; liver insulin resistance and inflammation; increased liver VLDL synthesis and secretion; reduced clearance of triglyceride-rich lipoproteins; presence of small, dense LDL particles; and reduced HDL cholesterol levels are among the many metabolic alterations closely related to this condition. Age, gender, genetics, and ethnicity are broad etiological factors contributing to variation in visceral adipose tissue accumulation. Specific mechanisms responsible for proportionally increased visceral fat storage when facing positive energy balance and weight gain may involve sex hormones, local cortisol production in abdominal adipose tissues, endocannabinoids, growth hormone, and dietary fructose. Physiological characteristics of abdominal adipose tissues such as adipocyte size and number, lipolytic responsiveness, lipid storage capacity, and inflammatory cytokine production are significant correlates and even possible determinants of the increased cardiometabolic risk associated with visceral obesity. Thiazolidinediones, estrogen replacement in postmenopausal women, and testosterone replacement in androgen-deficient men have been shown to favorably modulate body fat distribution and cardiometabolic risk to various degrees. However, some of these therapies must now be considered in the context of their serious side effects. Lifestyle interventions leading to weight loss generally induce preferential mobilization of visceral fat. In clinical practice, measuring waist circumference in addition to the body mass index could be helpful for the identification and management of a subgroup of overweight or obese patients at high cardiometabolic risk.

Effect of a six-week national cholesterol education program step 1 diet on plasma sex hormone-binding globulin levels in overweight premenopausal women

BACKGROUND

Low circulating sex hormone-binding globulin (SHBG) concentrations have been associated with the presence of several features of the metabolic syndrome in both men and women. Nutritional factors including dietary lipids and fibers in particular have been suggested to modulate plasma SHBG levels.

METHODS

The primary objective of the present study was to investigate the effect of an oat bran-rich supplement in conjunction with the National Cholesterol Education Program (NCEP) Step 1 diet (< 30% of total energy from fat, < 10% of energy from saturated fat, and < 300 mg cholesterol per day) on plasma SHBG levels in 35 overweight premenopausal women. Subjects (age 38.6 +/- 7.4 years) had normal menstrual cycles and were tested in the midluteal phase. Since no effect of the oat bran supplement was observed on plasma SHBG levels, data were analyzed according to the 6-week NCEP Step 1 diet.

RESULTS

The NCEP Step 1 nutritional intervention caused a significant decrease in energy intake ( -11%, p < 0.05), percent fat intake (-10%, p < 0.005), as well as saturated (-20%, p < 0.005) and monounsaturated (-10%, p < 0.05) fatty acid intake. Body mass index (BMI) decreased slightly but significantly (from 29.2 +/- 4.5 to 28.8 +/- 4.3 kg/m(2), p < 0.005). Plasma SHBG levels increased significantly (from 70.6 +/- 17.7 to 79.9 +/- 15.3 pmol/L, p < 0.0005) following the 6-week NCEP Step 1 diet, whereas plasma insulin levels were not modified significantly. Significant correlations were observed between the change in plasma SHBG levels and baseline BMI (r = 0.36, p < 0.04), as well as baseline (r = -0.42, p < 0.05) and postintervention (r = -0.35, p < 0.05) HDL cholesterol levels.

CONCLUSIONS

We observed that a 6-week NCEP Step 1 diet significantly increased plasma SHBG levels, despite the finding that fasting insulin was not modified. Further studies are needed to elucidate physiological mechanisms underlying a direct effect of dietary composition on SHBG production by the liver.

Effects of aerobic exercise training on serum sex hormone binding globulin, body fat index, and metabolic syndrome factors in obese postmenopausal women

BACKGROUND

The percentage of obese postmenopausal women with metabolic syndrome is rising, and physical factors associated with the metabolic syndrome prevalence or incidence are also rising, including high body mass index (BMI), visceral fat area (VFA), low plasma sex hormone-binding globulin (SHBG) levels, and low cardiorespiratory fitness. Therefore, we investigated the influence of aerobic exercise on SHBG, body fat index (BFI), and metabolic syndrome factors in obese postmenopausal Korean women.

METHODS

Thirty healthy postmenopausal, women aged 53.46 ± 2.4 years and with over 32% body fat, were randomly assigned to an aerobic exercise group (EX; n=15) or to a "nonexercise" control (Con; n=15) group. The primary outcome measurements were serum SHBG, lipid profiles, insulin levels, and metabolic syndrome factors. Secondary outcome measurements were body composition, VFA, blood pressure (BP), and homeostasis model assessment of insulin resistance (HOMA-IR).

RESULTS

Posttraining body weight and BFI (P<0.05), total cholesterol, glucose, and insulin levels (P<0.01), BP, and HOMA-IR (P<0.001) decreased, whereas SHBG (P<0.001) and metabolic syndrome factors (P<0.01) improved in the exercise group but not in the control group. SHBG levels also showed a significant positive correlation with high-density lipoprotein cholesterol (HDL-C) and significant negative correlations withglucose, diastolic blood pressure, fat mass, BMI, and percent body fat (P<0.05).

CONCLUSIONS

Our findings indicate that aerobic exercise improves body composition, SHBG, insulin levels, and metabolic syndrome factors. These findings suggest that in obesepostmenopausal Korean women, 16 weeks of aerobic exercise is effective for preventing the metabolic syndrome caused by obesity.

Obesity: considerations about etiology, metabolism, and the use of experimental models

Studies have been conducted in order to identify the main factors that contribute to the development of obesity. The role of genetics has also been extensively studied. However, the substantial augmentation of obesity prevalence in the last 20 years cannot be justified only by genetic alterations that, theoretically, would have occurred in such a short time. Thus, the difference in obesity prevalence in various population groups is also related to environmental factors, especially diet and the reduction of physical activity. These aspects, interacting or not with genetic factors, could explain the excess of body fat in large proportions worldwide. This article will focus on positive energy balance, high-fat diet, alteration in appetite control hormones, insulin resistance, amino acids metabolism, and the limitation of the experimental models to address this complex issue.

Sex hormone-binding globulin levels and obesity in women with gestational diabetes: relationship with infant birthweight

Our objective was to determine whether sex hormone-binding globulin (SHBG) concentrations are associated with gestational diabetes mellitus (GDM) and whether this association is independent of prepregnancy body mass index (BMI). The relationship between maternal SHBG concentrations and birthweight in the offspring was also examined. The study included 47 women (20 with GDM, 27 controls). GDM screening and fasting serum SHBG measurements were performed at 26.1 ± 3.7 weeks of pregnancy. A trend was observed for significantly lower SHBG concentrations in GDM patients (179 ± 36 vs. 195 ± 36 nmol/l, p ≤ 0.08). Prepregnancy BMI and BMI at the time of GDM screening were both correlated with SHBG concentrations (r = -0.49 and r =  -0.53, respectively; p ≤ 0.001). In multivariate regression analyses, only prepregnancy BMI or BMI at the time of GDM screening remained significant predictors of GDM risk [odds ratio (OR):1.23, 95% confidence interval (CI):1.06-1.47, p ≤ 0.01 and OR:1.18, 95% CI:1.02-1.39, p ≤ 0.02] while SHBG level did not. On the other hand, 10.7% of the variance in birthweight was explained by SHBG concentrations (p ≤ 0.01) independent of the presence of GDM, parity, maternal age, maternal prepregnancy BMI, maternal height, and offspring sex. In conclusion, although SHBG concentration is not an independent predictor of GDM risk when obesity is considered, it is a significant predictor of infant birthweight independent of GDM and prepregnancy BMI.

Relation between androgens and cardiovascular risk factors in a young population

OBJECTIVE

The relationship between androgens and blood pressure, insulin resistance, lipid profile, adiponectin and hs-CRP in a young Middle-Eastern population has not been examined previously. We studied this relationship in a randomly selected population of Lebanese students.

METHODS

Three hundred and sixty-eight subjects (201 men and 167 women) aged 18-30 years were included in the study. Anthropometric and biological parameters [waist circumference (WC), systolic and diastolic blood pressure (SBP and DBP), triglycerides, total cholesterol, HDL cholesterol, homeostasis model assessment of insulin resistance (HOMA-IR), total testosterone (TT), dehydroepiandrostenedione sulphate (DHEAS), sex hormone-binding globulin (SHBG), adiponectin (ADP) and hs-CRP] were measured.

RESULTS

In men, there were inverse associations of both TT and SHBG with body mass index (BMI), WC, HOMA-IR, triglycerides and hs-CRP. After adjustment for major confounders (BMI, WC, age and smoking), associations disappeared except for those between TT and hs-CRP, and for SHBG HOMA-IR, hs-CRP and triglycerides. In women, only SHBG was inversely associated with BMI, WC, HOMA-IR and hs-CRP and positively correlated with adiponectin. Except for the association between SHBG and adiponectin, these correlations disappeared after adjustment for confounders. Although DHEAS appeared to correlate negatively with blood pressure in men, this relationship disappeared after adjustment for confounders, while a relationship between DHEAS and triglycerides in women persisted after such adjustment. In multivariate regression analysis, SHBG was an independent predictor of hs-CRP, triglycerides and HOMA-IR in men and of adiponectin in women.

CONCLUSION

Our results suggest that SHBG is independently associated with HOMA-IR, adiponectin, hs-CRP and triglycerides. A gender difference in these associations is observed. Further studies are needed to elucidate these findings.

Patterns of testicular activity in captive and wild Canada lynx (Lynx canadensis)

Canada lynx are listed as a threatened species in the contiguous US. Understanding the reproductive characteristics (i.e., mating system, behavior, physiology) of a species is useful for ensuring effective in situ and ex situ management plans. The goal of this study was to describe patterns of androgen expression in both captive and wild male Canada lynx using fecal hormone metabolite analysis. Among captive lynx, juvenile and castrated males had lower concentrations of fecal androgens (fA) than intact males, thereby demonstrating that the assay detects biologically meaningful differences in testicular activity. We found that captive males in general had much higher fA levels than wild males. All males showed strong seasonal variation in fA concentrations, with significantly higher levels being expressed during the breeding season (February and March) than during the non-breeding season. Among captive males, variation in seasonal fA levels did not correlate with latitude. Finally, males housed with intact cage-mates (either male or female) had significantly higher fA levels than males housed alone or with a neutered cage-mate.

Patterns of ovarian and luteal activity in captive and wild Canada lynx (Lynx canadensis)

Canada lynx face some unique breeding restrictions, which may have implications for population viability and captive management. The goal of this study was to improve our understanding of basic reproductive physiology in Canada lynx. Using fecal hormone metabolite analysis, we established normative patterns of fecal estrogen (fE) and progestagen (fP) expression in captive and wild female Canada lynx. Our results indicate that Canada lynx have persistent corpora lutea, which underlie their uncharacteristic fP profiles compared to other felids. Thus, fP are not useful for diagnosing pregnancy in Canada lynx. We also found that Canada lynx are capable of ovulating spontaneously. Captive females had higher concentrations of fE and fP than wild females. Both populations exhibit a seasonal increase in ovarian activity (as measured by fE) between February and April. Finally, there was evidence of ovarian suppression when females were housed together.

Effects of testosterone supplementation on markers of the metabolic syndrome and inflammation in hypogonadal men with the metabolic syndrome: the double-blinded placebo-controlled Moscow study

OBJECTIVE

Men with the metabolic syndrome (MetS) have low plasma testosterone (T) levels. The aim of this study was to establish whether the normalization of plasma T improves the features of the MetS.

DESIGN

A randomized, placebo-controlled, double-blinded, phase III trial of 184 men suffering from both the MetS and hypogonadism.

PATIENTS

One hundred and eighty-four men, aged 35-70, with the MetS and hypogonadism (baseline total T level <12·0 nm or calculated free T level <225 pm.), recruited in the outpatient andrology and urology clinic, Research Center for Endocrinology in Moscow, Russia.

INTERVENTION

Treatment for 30 weeks with either parenteral T undecanoate (n = 113; TU; 1000 mg IM) or placebo (n = 71), administered at baseline, and after 6 and 18 weeks. One hundred and five (92·9%) men receiving TU and 65 (91·5%) receiving placebo completed the trial.

MEASUREMENTS

Body weight, body mass index (BMI), waist circumference (WC), hip circumference, waist-to-hip ratio, insulin, leptin, glucose, cholesterol, triglycerides, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, C-reactive protein (CRP), interleukin-1-beta (IL-1β), interleukin-6 (IL-6), interleukin-10 (IL-10) and tumour necrosis factor-alpha (TNF-α).

RESULTS

There were significant decreases in weight, BMI and WC in the TU vs placebo group. Levels of leptin and insulin also decreased, but there were no changes in serum glucose or lipid profile. Of the inflammatory markers, IL-1β, TNF-α and CRP decreased, while IL-6 and IL-10 did not change significantly.

CONCLUSIONS

Thirty weeks of T administration normalizing plasma T in hypogonadal men with the MetS improved some components of the MetS and a number of inflammatory markers.

Sex hormone-binding globulin levels and metabolic syndrome and its features in adolescents

BACKGROUND

Low levels of sex hormone-binding globulin (SHBG) are associated with obesity, insulin resistance, and metabolic syndrome (MS) in men and women, and it has been suggested that SHBG could be a useful marker for MS risk.

OBJECTIVE

The aim of this study was to analyze the relationship of SHBG levels with MS and its components in Spanish adolescents.

METHODS

The sample population of this cross-sectional study was comprised of 386 male and 429 female adolescents, aged 12-16 yr. Anthropometric parameters and blood pressure (BP) were measured. Total cholesterol, high-density lipoprotein (HDL)-cholesterol, insulin, glucose, and SHBG levels were determined. The pediatric International Diabetes Federation (IDF) definition was used to classify adolescents for MS.

RESULTS

SHBG levels were lower in adolescents with MS or with some MS features. More than 90% of the abdominally obese adolescents were in the lowest and medium SHBG tertiles. In girls, BP was significantly higher in the lowest SHBG tertile than in the two others, whereas in boys BP levels were significantly higher in the lowest and medium tertiles than in the highest one. Insulin levels and homeostasis model assessment (HOMA) index were also significantly higher in the lowest SHBG tertile than in the two others.

CONCLUSIONS

The associations of SHBG with MS and its components, such as abdominal obesity, high BP or insulin levels, are already present in normal adolescents. This may suggest the possibility of using SHBG levels as a biomarker for MS risk in adolescents as well as adults.

Smoking among premenopausal women is associated with increased risk of low bone status: the JPOS Study

The impact of smoking on peak bone density has not been conclusively established. We examined how smoking exposure influences bone mineral density (BMD) or the risk of low bone status in premenopausal women. We conducted a baseline survey with a representative sample of Japanese women in 1996. The effect of current and former smokers (ever-smoker) was investigated with 789 premenopausal women aged 20-40 years. The multiple regression with stepwise method was used to identify significant determinants for BMD or the risk of low bone status (T-score < -1) with age, height, weight, calcium intake, coffee consumption, exercise habits, level of daily activity, parity >or= 1, and smoking as explanatory variables. The smoking effect was determined after adjusting for age, height, weight, and significant variables in the multiple regression with stepwise method. Ever-smoker was significantly associated with decreased lumbar BMD adjusted for age, height, and weight. The odds ratio of an ever-smoker for low bone status at the lumbar spine was 2.03 (95% CI 1.12, 5.82) adjusted for age, height, weight, and parity. The odds ratio for low bone status at the lumbar spine was 1.59 (95% CI 0.65, 3.91) and 2.55 (95% CI 1.12, 5.82) in those with less than 3 pack-years of tobacco use and in those with 3 or more pack-years of tobacco use, respectively. These values were adjusted for age, height, weight, and parity using a never-smoker as a reference. Cumulative smoking exposure may be associated with increased risk of low bone status among premenopausal women.

Sex hormone-binding globulin and lipid profile in pubertal children

Men and women have different lipid profiles throughout life, related to changes in sex hormones; and this has been associated with sex-related differences in the prevalence of coronary heart disease. The influence of sex hormone changes during puberty on the lipid profile has been reported, but levels of sex hormone-binding globulin (SHBG) (the specific plasma binding protein of sex hormones) have not been evaluated even though its regulatory role might be crucial. The aim of this study was to analyze the relationship between sex hormones and SHBG and changes in plasma lipid levels during puberty. Our population-based sample included 370 healthy schoolchildren (175 male and 195 female), ranging from 12 to 15 years old. High-density lipoprotein cholesterol (HDL-C) levels were significantly lower in 15-year-olds than in younger boys, and apolipoprotein (apo) A-I levels steeply decreased across the studied age groups. Parallel to these changes, testosterone levels increased whereas SHBG decreased as age increases in boys. In girls, no significant differences were observed in these variables among the age groups. Testosterone and SHBG were highly correlated with anthropometric variables. Sex hormone-binding globulin was negatively associated with triglycerides (TG) in both sexes, remaining statistically significant after further adjustment for age and body mass index (BMI) in girls. Sex hormone-binding globulin was the only predictive variable for HDL-C and TG in multiple linear regression analysis, after adjustment by BMI, in both sexes, accounting for 10% of the variance of HDL-C in boys and for around 5% of the variance of TG in both sexes. In boys, testosterone and SHBG remained significantly correlated to apo A-I levels, even after adjusting for age and BMI, and were the most important predictive variables for apo A-I in multiple linear regression analysis. In conclusion, SHBG levels are related to a decrease in HDL-C and apo A-I levels during puberty in boys and to a decrease in TG levels during puberty in both sexes.

Influence of age and obesity on serum estradiol, estrone, and sex hormone binding globulin concentrations following oral estrogen administration in postmenopausal women

OBJECTIVE

Hormone therapy (HT) increases the risk of venous thrombosis and stroke. Risk of venous thrombosis and stroke is higher in older, overweight, and obese women using HT. However, the impact of age and obesity on estrogen concentrations among HT users is not well defined.

METHOD

We measured serum levels of estrone, total and free estradiol, and SHBG in 180 postmenopausal women participating in the Estrogen in the Prevention of Atherosclerosis Trial (EPAT), 91 receiving estradiol therapy (ET) and 89 taking placebo, every 6 months over 2 yr. Mean on-trial levels of estrogens and SHBG were compared across age, body mass index (BMI), and waist to hip ratio categories among ET users and placebo separately.

RESULTS

Among the ET users, total (P = 0.01) and free estradiol (P = 0.002) were significantly directly associated with BMI adjusted for age. SHBG was inversely related to waist to hip ratio adjusted for age (P = 0.005). Age was not associated with any of the estrogen or SHBG concentrations in ET or placebo groups. BMI was positively associated with estrone concentrations among older but not younger ET users (P for interaction = 0.03).

CONCLUSION

Overweight and obese women using ET attain greater concentrations of estrogen compared to women with normal BMI, whereas ET users with abdominal obesity attain lower SHBG levels. Obese older women using ET have the highest concentration of estrone. It may be useful to consider age and obesity when prescribing HT to minimize the risk of venous thrombosis or stroke in postmenopausal women. Further research regarding relationships among circulating hormone levels and risk for these conditions is required to substantiate this conclusion.

Dietary beta-tocopherol and linoleic acid, serum insulin, and waist circumference predict circulating sex hormone-binding globulin in premenopausal women

Reduced levels of circulating sex hormone-binding globulin (SHBG) are implicated in the etiology of sex steroid-related pathologies and the metabolic syndrome. Dietary correlates of serum SHBG remain unclear and were studied in a convenient cross-sectional sample of healthy 30- to 40-y-old women (n = 255). By univariate analyses, serum SHBG correlated negatively with several indices of the metabolic syndrome, such as BMI, waist circumference, hip circumference (r = -0.36 to -0.44; P < 0.0001), fasting serum insulin (r = -0.41; P < 0.0001), serum triglycerides (r = -0.27; P < 0.0001), serum glucose (r = -0.23; P < 0.001), and plasma testosterone (r = -0.19; P = 0.002). Serum SHBG correlated positively with serum HDL-cholesterol (r = 0.33; P < 0.0001), plasma progesterone (r = 0.17; P = 0.007), and dietary intake of beta-tocopherol (r = 0.17; P = 0.006), and negatively with that of fructose (r = -0.13; P = 0.04). Principal component analysis (PCA) extracted 12 nutrient factors with eigenvalues > 1.0 from 54 nutrients and vitamins in food records. Multivariate regression analyses showed that the PCA-extracted nutrient factor most heavily loaded with beta-tocopherol and linoleic acid (P = 0.03) was an independent positive predictor of serum SHBG. When individual nutrients were the predictor variables, beta-tocopherol (P = 0.002), but not other tocopherols or fatty acids (including linoleic acid), was an independent positive predictor of serum SHBG. Circulating insulin (P = 0.02) and waist circumference (P = 0.002), but not serum lipids, were negative independent predictors of SHBG in all regression models. Additional studies are needed in women of other age groups and men to determine whether consumption of foods rich in beta-tocopherol and/or linoleic acid may increase serum SHBG concentrations and may thereby decrease the risk for metabolic syndrome and reproductive organ cancer.

Associations of endogenous sex hormones and sex hormone-binding globulin with lipid profiles in aged Japanese men and women

BACKGROUND

The associations of endogenous estrogen with lipid profiles and insulin resistance were conflicting in both men and women. We determined the associations of serum estradiol level and free estradiol index (FEI) with lipid profiles and insulin resistance in aged Japanese men and women.

METHODS

One hundred seventy-four men and 208 postmenopausal women aged from 50 to 85 y were included in this study. Lipid profiles, fasting glucose and insulin as well as estradiol, testosterone, dehydroepiandrosterone-sulfate (DHEA-S) and sex hormone-binding globulin (SHBG) in serum were measured.

RESULTS

Serum estradiol concentration in men showed a significant and negative correlation with high density lipoprotein-cholesterol (HDL-C) concentration and a significant and positive correlation with triglyceride (TG) after adjustment for age and body mass index (BMI). In addition, estradiol level was positively correlated with insulin and HOMA index. In women, serum levels of estradiol and testosterone were not correlated with lipid profiles and insulin resistance. SHBG concentration was negatively correlated with TG after adjustment for age and BMI in women.

CONCLUSION

Endogenous estradiol level is associated with unfavorable lipid profiles and insulin resistance in aged men. In aged women, SHBG level is associated with favorable lipid profiles.

Androgens and body fat distribution

An important sex difference in body fat distribution is generally observed. Men are usually characterized by the android type of obesity, with accumulation of fat in the abdominal region, whereas women often display the gynoid type of obesity, with a greater proportion of their body fat in the gluteal-femoral region. Accordingly, the amount of fat located inside the abdominal cavity (intra-abdominal or visceral adipose tissue) is twice as high in men compared to women. This sex difference has been shown to explain a major portion of the differing metabolic profiles and cardiovascular disease risk in men and women. Association studies have shown that circulating androgens are negatively associated with intra-abdominal fat accumulation in men, which explains an important portion of the link between low androgens and features of the metabolic syndrome. In women, the low circulating sex hormone-binding globulin (SHBG) levels found in abdominal obesity may indirectly indicate that elevated free androgens are related to increased visceral fat accumulation. However, data on non SHBG-bound and total androgens are not unanimous and difficult to interpret for total androgens. These studies focusing on plasma levels of sex hormones indirectly suggest that androgens may alter adipose tissue mass in a depot-specific manner. This could occur through site-specific modulation of preadipocyte proliferation and/or differentiation as well as lipid synthesis and/or lipolysis in mature adipocytes. Recent results on the effects of androgens in cultured adipocytes and adipose tissue have been inconsistent, but may indicate decreased adipogenesis and increased lipolysis upon androgen treatment. Finally, adipose tissue has been shown to express several steroidogenic and steroid-inactivating enzymes. Their mere presence in fat indirectly supports the notion of a highly complex enzymatic system modulating steroid action on a local basis. Recent data obtained in both men and women suggest that enzymes from the aldoketoreductase 1C family are very active and may be important modulators of androgen action in adipose tissue.

Adiposity, the metabolic syndrome, and breast cancer in African-American and white American women

Breast cancer, the second most common cause of cancer-related deaths in American women, varies substantially in incidence and mortality according to race and ethnicity in the United States. Although the overall incidence of breast cancer among African-American (AA) women is lower than in white American women, this cancer is more common in young premenopausal AA women, and AA breast cancer patients of all ages are more likely to have advanced disease at diagnosis, higher risk of recurrence, and poorer overall prognosis. Epidemiological studies indicate that these differences may be attributable in part to variation in obesity and body fat distribution. Additionally, AA women more frequently exhibit breast cancer with an aggressive and metastatic phenotype that may also be attributable to the endocrine and metabolic changes associated with upper body obesity. These changes include both elevated estrogen and androgen bioactivity, hyperinsulinemia, and perturbations of the adipokines. Type 2 diabetes and the metabolic syndrome, which are more common in AA women, have also been associated with breast cancer risk. Moreover, each of the individual components of the syndrome has been associated with increased breast cancer risk, including low levels of the adipocytokine, adiponectin. This review explores the specific roles of obesity, body fat distribution (particularly visceral and sc adipose tissue), type 2 diabetes, metabolic syndrome, and adipocytokines in explaining the differential patterns of breast cancer risk and prognosis between AA and white American women.

Associations of adiponectin with sex hormone-binding globulin levels in aging male and female populations

BACKGROUND

Changes with aging in serum gonadal hormones, sex hormone-binding globulin (SHBG) and adiponectin, which are involved in insulin resistance and metabolic syndrome, are different in men and women. We examined the relationships of serum adiponectin concentrations with serum concentrations of hormones and SHBG in men and women.

METHODS

One hundred fifty-four men and 180 women aged from 50 to 85 years were included in the cross-sectional study. Serum concentrations of testosterone, estradiol, dehydroepiandrosterone-sulfate, SHBG and adiponectin were measured in men and women.

RESULTS

Serum adiponectin concentration showed a significant positive correlation with serum SHBG concentration in men and women (r=0.404, p<0.0001 and r=0.348, p<0.0001, respectively). Multiple regression analysis also showed that SHBG was the significant predictor for adiponectin in men and women. Serum adiponectin concentration in men showed a significant positive correlation with total testosterone concentration, but that in women was not significantly correlated with total testosterone concentration. Both adiponectin and SHBG concentrations in men (r=-0.222, p=0.0051 and r=-0.334, p<0.0001, respectively) and women (r=-0.281, p=0.0014 and r=-0.251, p=0.0048, respectively) showed significant negative correlations with the homeostasis model assessment (HOMA) index.

CONCLUSION

Correlations between adiponectin and SHBG were significantly positive in both men and women, and both adiponectin and SHBG might be involved in insulin resistance in both sexes.

Effect of insulin sensitivity on SHBG levels in premenopausal versus postmenopausal obese women

This study was performed to evaluate the impact of insulin sensitivity on sex hormone-binding globulin (SHBG) and sex steroids in premenopausal and postmenopausal euthyroid obese women. A total of 227 women were eligible for this study. All were euthyroid, obese, and overweight; ages ranged from 25 to 69 years. Women were divided into premenopausal (n=151) and postmenopausal (n=76) groups. SHBG, sex steroids, thyrotropin, fasting and postprandial glucose, lipid profile, uric acid, serum insulin, and blood pressure were measured. No significant difference was found in mean SHBG levels between premenopausal and postmenopausal women. The investigators observed that during transition from premenopause to postmenopause, SHBG levels increased in insulin-sensitive women in the postmenopausal group; however, SHBG levels decreased in insulinresistant women. It was concluded that SHBG blood concentration factors are likely to change during transition from premenopause to postmenopause. The positive effect of estradiol on SHBG levels is probably stronger in premenopausal women than in postmenopausal women. It has been noted that after menopause, the impact of insulin resistance on SHBG level seems more important than the effect of estradiol.

Adiposity, type 2 diabetes and the metabolic syndrome in breast cancer

Upper body obesity and the related metabolic disorder type 2 diabetes have been identified as risk factors for breast cancer, and associated with late-stage disease and a poor prognosis. Components of the metabolic syndrome, including visceral adiposity, insulin resistance, hyperglycemia and hyperinsulinemia, with or without clinically manifest diabetes mellitus, low serum high-density lipoprotein cholesterol and hypertension have all been related to increased breast cancer risk. The biochemical mechanisms include extraglandular oestrogen production, reduced sex hormone-binding globulin with consequent elevation of the bioactive plasma free oestradiol and increased insulin biosynthesis, all of which exert mitogenic effects on both untransformed and neoplastic breast epithelial cells. Obesity, type 2 diabetes and the metabolic syndrome also have in common an increased production of leptin and a decreased production of adiponectin by adipose tissue, with consequent elevations and reductions, respectively, in the circulating levels of these two adipokines. These changes in plasma leptin and adiponectin, acting through endocrine and paracrine mechanisms, have been associated in several studies with an increase in breast cancer risk and, perhaps, to more aggressive tumours; studies in vitro showed that leptin stimulates, and adiponectin inhibits, tumour cell proliferation and the microvessel angiogenesis which is essential for breast cancer development and progression.

Interrelationship Between Insulin Resistance and Menopause on the Metabolic Syndrome and Its Individual Component Among Nondiabetic Women in the Kinmen Study

BACKGROUND

The literature to date is not clear as to whether any interactive effect exists between insulin resistance and menopause on the metabolic syndrome and its individual components. We explored this issue in 4107 homogeneous, nondiabetic Chinese women in the Kinmen Study.

METHODS

Overnight fasting blood samples were drawn for glucose, insulin, lipid, and other biochemical measurements. Demographic and clinical variables including body mass index, waist circumference, and blood pressure were measured and documented during face-to-face interviews with structured questionnaires. Menstrual history was used to define menopause as the absence of menses for 12 consecutive months.

RESULTS

Approximately 16% of premenopausal women (390/2423) were insulin-resistant. After adjustment for age, body mass index, lifestyle, and diet, both menopause and insulin resistance were independently and significantly correlated with metabolic syndrome. For each component of the metabolic syndrome, besides the main effect, the interaction (insulin resistance x menopause) had significant correlation with systolic blood pressure, diastolic blood pressure, and waist circumference.

CONCLUSIONS

Both insulin resistance and menopause have significant effects on metabolic syndrome independent of age and obesity. In premenopausal and nondiabetic women, various degrees of insulin resistance exist. The synergistic contribution of insulin resistance and menopause to components of the metabolic syndrome were observed with systolic blood pressure, diastolic blood pressure, and waist circumference. This requires further study.

Association between hormones and metabolic syndrome in older Italian men

OBJECTIVES

To determine whether low levels of testosterone, sex hormone binding globulin (SHBG), insulin-like growth factor-1 (IGF-1), and dehydroepiandrosterone sulfate (DHEAS) and high levels of cortisol and leptin would be associated with metabolic syndrome (MS).

DESIGN

Cross-sectional.

SETTING

Population-based sample of older Italian men.

PARTICIPANTS

Four hundred fifty-two men aged 65 and older enrolled in the Invecchiare in Chianti (InCHIANTI) study.

MEASUREMENTS

Complete data on testosterone, cortisol, DHEAS, SHBG, fasting insulin, IGF-1 and leptin. MS was defined according to Adult Treatment Panel III criteria.

RESULTS

MS was present in 73 men (15.8% of the sample). After adjusting for confounders, total testosterone (P < .05) and log (SHBG) (P < .001) were inversely associated, whereas log (leptin) was positively associated with MS (P < .001). Independent of age, log (SHBG) was positively associated with high-density lipoprotein cholesterol (P < .05) and negatively associated with abdominal obesity (P < .001) and triglycerides (P < .001). Log (leptin) was significantly associated with each component of MS. Cortisol, DHEAS, free and bioavailable testosterone, and IGF-1 were not associated with MS. Having three or more hormones in the lower (for hormones lower in MS) or the upper (for hormones higher in MS) quartile was associated with three times the risk of being affected by MS (odds ratio = 2.8, 95% confidence interval = 1.3-6.9) (P = .005), compared with not having this condition.

CONCLUSION

Total testosterone and SHBG are negatively and leptin is positively associated with MS in older men. Whether specific patterns of hormonal dysregulation predict the development of MS should be tested in longitudinal studies.

Association of hormonal dysregulation with metabolic syndrome in older women: data from the InCHIANTI study

Metabolic syndrome (MetS) is a strong risk factor for type 2 diabetes and cardiovascular disease. Conditions associated with hyperandrogenism are often associated with glucose intolerance and other features of MetS in young women. As the prevalence of MetS increases with age and is probably multifactorial, it is reasonable to hypothesize that age-related changes in androgens and other hormones might contribute to the development of MetS in older persons. However, this hypothesis has never been tested in older women. We hypothesized that high levels of testosterone, dehydroepiandrosterone sulfate (DHEA-S), and cortisol and low levels of sex hormone-binding globulin (SHBG) and IGF-I would be associated with MetS in a representative cohort of older Italian women independently of confounders (including inflammatory markers). After exclusion of participants on hormone replacement therapy and those with a history of bilateral oophorectomy, 512 women (>/=65 yr) had complete data on testosterone, cortisol, DHEA-S, SHBG, fasting insulin, total and free IGF-I, IL-6, and C-reactive protein (CRP). MetS was defined according to ATP-III criteria. Insulin resistance was calculated according to HOMA. MetS was found in 145 women (28.3%). Participants with vs. those without MetS had higher age-adjusted levels of bioavailable testosterone (P < 0.001), IL-6 (P < 0.001), CRP (P < 0.001), and HOMA (P < 0.001) and lower levels of SHBG (P < 0.001). After adjustment for potential confounders, participants with decreased SHBG had an increased risk of MetS (P < 0.0001) vs. those with low SHBG. In a further model including all hormones and confounders, log SHBG was the only independent factor associated with MetS (OR: 0.44, 95% CI 0.21-0.91, P = 0.027). In older women, SHBG is negatively associated with MetS independently of confounders, including inflammatory markers and insulin resistance. Further studies are needed to support the notion that raising SHBG is a potential therapeutic target for prevention and treatment of MetS.

Low sex hormone-binding globulin is associated with the metabolic syndrome in postmenopausal women

Although an association between the metabolic syndrome and hyperandrogenism has been suggested in women with polycystic ovarian syndrome, few studies have investigated this relationship in postmenopausal women. We measured estradiol, testosterone, and sex hormone-binding globulin (SHBG) and calculated the free androgen index (FAI) in 212 postmenopausal women not using hormone therapy in the Women's Health Study. A modified definition of the metabolic syndrome (3 or more of the following: abdominal obesity, hypertriglyceridemia, low high-density lipoprotein, elevated blood pressure, and abnormal glucose metabolism) from the Third Report of the National Cholesterol Education Program Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults was used. Women with the metabolic syndrome had higher mean levels of estradiol, testosterone, and FAI values and lower SHBG levels. Higher FAI and lower SHBG were associated with all components of the metabolic syndrome. After adjustment for BMI and other factors, women in the highest tertile of FAI had an odds ratio of 12.6 (95% confidence interval, 3.8-41.6) for the metabolic syndrome, whereas those in the lowest SHBG tertile had an odds ratio of 7.3 (95% confidence interval, 2.7-19.8). When stratified by body mass index, the associations with high FAI and low SHBG remained significant even in women with body mass index less than 26.7 kg/m2. An androgenic hormone profile is associated with both the individual components of the metabolic syndrome and clustering of metabolic abnormalities in postmenopausal women.

Serum sex hormone-binding globulin levels show too much variability to be used effectively as a screening marker for insulin resistance in women with polycystic ovary syndrome

OBJECTIVE

To evaluate the relationship between serum sex hormone-binding globulin (SHBG) and parameters of insulin sensitivity in women with polycystic ovary syndrome (PCOS) and controls, and determine the feasibility of using SHBG levels to predict insulin resistance.

DESIGN

Evaluation of a prospectively collected database.

SETTING

University reproductive center.

PATIENT(S)

A total of 21 women with PCOS and 17 controls.

INTERVENTION(S)

Oral glucose tolerance test.

MAIN OUTCOME MEASURE(S)

Correlations of serum SHBG and parameters of insulin sensitivity.

RESULT(S)

[1] Among all participants, SHBG levels indicated a correlation between the fasting glucose-to-insulin (GI) ratio and the quantitative insulin sensitivity check index (QUICKI). Participants with PCOS demonstrated significant correlations of SHBG and fasting GI ratio, 1-hour postglucola insulin levels, and random 17-hydroxyprogesterone (17ohP4) levels. Among controls, SHBG and fasting serum glucose and 2-hour postglucola serum glucose levels were associated. [2] Participants with PCOS and lean controls exhibited different glucose and insulin responses to 75 g of glucose at 1 and 2 hours postchallenge, resulting in paradoxically similar GI ratios.

CONCLUSION(S)

[1] Although certain parameters of insulin status and serum SHBG demonstrated statistically significant correlation coefficients, these relationships are weak and SHBG cannot be used as a predictor of insulin resistance. [2] The post-glucose load GI ratio cannot be used to determine the magnitude of insulin resistance.

Anthropometric measures, endogenous sex steroids and breast cancer risk in postmenopausal women: a study within the EPIC cohort

In a large case-control study on breast cancer risk and serum hormone concentrations, nested within the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort, we examined to what extent the relationship of excess body weight with breast cancer risk may be explained by changes in sex steroids. Height, weight, waist and hip circumferences, and serum measurements of testosterone [T], androstenedione [Delta4], dehydroepiandrosterone sulphate [DHEAS], estradiol [E2], estrone [E1] and sex-hormone binding globulin [SHBG] were available for 613 breast cancer cases, and 1,139 matched controls, who were all menopausal at the time of blood donation. Free T [fT] and free E2 [fE2] were calculated using mass action equations. Breast cancer risk was related to body mass index (BMI) (RR = 1.11 [0.99-1.25], per 5 kg/m2 increase in BMI), and waist (RR = 1.12 [1.02-1.24], per 10 cm increase) and hip circumferences (RR = 1.14 [1.02-1.27], per 10 cm increase). The increase in breast cancer risk associated with adiposity was substantially reduced after adjustment for any estrogens, especially for fE2 (from 1.11 [0.99-1.25] to 0.99 [0.87-1.12], from 1.12 [1.02-1.24] to 1.02 [0.92-1.14] and from 1.14 [1.02-1.27] to 1.05 [0.93-1.18] for BMI, waist and hip circumferences, respectively). A modest attenuation in excess risk was observed after adjustment for fT, but the remaining androgens had little effect on the association of body adiposity with breast cancer. Our data indicate that the relationship of adiposity with breast cancer in postmenopausal women could be partially explained by the increases in endogenous estrogens, and by a decrease in levels of SHBG.

Metabolic syndrome throughout the menopausal transition: influence of age and menopausal status

OBJECTIVE

To assess the relationship between the main components of both the metabolic syndrome and insulin resistance and menopausal status in the menopausal transition.

METHODS

A total of 124 healthy women were divided into four groups according to their menstrual status: the first group consisted of 35 women in menopausal transition with menstrual bleeding (MTM) and with cycles between 35 and 80 days; the second group was composed of 29 women in menopausal transition with 3-6 months of amenorrhea (MTA). The third group consisted of 31 postmenopausal women (PostM) and the fourth group of 29 premenopausal women (PreM) with regular cycles. The metabolic syndrome was evaluated following the ATP III criteria. Evaluation of insulin resistance was made through the HOMA, QUICKI and McAuley indices and the triglycerides/high density lipoprotein (HDL) cholesterol ratio.

RESULTS

The triglycerides/HDL cholesterol ratio increased in MTM, MTA and PostM women in comparison with PreM women. A slight decrease in the QUIKI index (p = 0.06) and a decrease in the McAuley index (p < 0.001) were observed in MTM, MTA and PostM women in comparison to PreM women. The relative frequencies of metabolic syndrome in the four groups were: PreM, 0%; MTM, 20%; MTA, 21%; and PostM, 22% (p = 0.0001). The most frequent markers of the metabolic syndrome were increased waist circumference, low HDL cholesterol levels and hypertension. Linear regression between menopausal status and metabolic syndrome was lost when age was added to the model.

CONCLUSIONS

The frequency of metabolic syndrome increased from the time of the menopausal transition to the postmenopause. Abdominal obesity was the most frequent feature observed. Nevertheless, aging erased the effect of the menopause on the metabolic syndrome. In order to prevent cardiovascular disease, the metabolic syndrome must be evaluated from the time of the menopausal transition.

Contribution of age and declining androgen levels to features of the metabolic syndrome in men

Plasma dehydroepiandrosterone sulfate (DHEA-S) and testosterone levels both decline with age in healthy men. Features of the metabolic syndrome also show age-related deteriorations. We examined the relative contribution of age and declining androgen levels to features of the metabolic syndrome in men. In a sample of 130 nonsmoking men from the Quebec Family Study, we tested the hypothesis that age-related decreases in DHEA-S and testosterone levels would explain most of the variance in alterations of the metabolic profile associated with aging. As expected, we found that plasma DHEA-S and testosterone levels were negatively associated with age. Significant negative correlations were found between androgen levels and adiposity measures, body fat distribution, and metabolic risk variables. Statistical control for age eliminated correlations with DHEA-S, whereas age-adjusted associations between testosterone and most adiposity and metabolic variables remained significant. The percentage frequency of men characterized by 3 or more features of the metabolic syndrome increased with decreasing testosterone (8.9%-44.2%, chi2 = 15.89, P < .0005 ) and DHEA-S levels (8.9%-41.5%, chi2 = 13.02, P < .005). Logistic regression analyses showed that men in the upper tertile of testosterone levels had a lower risk of being characterized by 3 or more features of the metabolic syndrome (odds ratio = 0.24, P < .04) independent of age, whereas tertiles of DHEA-S levels were not related to the metabolic syndrome independent of age. In conclusion, results suggest that age per se is an important correlate of the associations between DHEA-S and metabolic variables, whereas the association of plasma testosterone levels to features of the metabolic syndrome appears to be independent of age.