Editorial: Clinical relevance of racial and ethnic differences in sex steroids

The cutaneous effects of androgens and androgen-mediated sebum production and their pathophysiologic and therapeutic importance in acne vulgaris

Background: The recognition of an association between the development of acne vulgaris (AV) and pubertal hormonal changes during adolescence dates back almost 100 years. Since these formative observations, a significant role of circulating hormones in the pathophysiology of AV and other cutaneous disorders has been established.Aims: This review article aims to provide an overview of clinical and preclinical evidence supporting the influences of androgens on the skin and their therapeutic importance in AV pathophysiology.Results: The cutaneous effects of hormones are attributable, to a large extent, to the influence of steroid hormones, particularly androgens, on sebocyte development and sebum production in both sexes. Androgen-mediated excess sebum production is implicated as a necessary early step in AV pathophysiology and is therefore considered an important therapeutic target in AV treatment. Although the local production and/or activity of androgens within the skin is believed to be important in AV pathophysiology, it has received limited therapeutic attention.Conclusions: We have summarized the current evidence in support of the therapeutic benefits of targeted hormonal treatment to decrease androgen-stimulated sebum production for the effective and safe treatment of AV in both male and female patients.

Low endogenous estradiol levels are associated with elevated risk of cardiovascular disease mortality in young and middle-aged men in the United States

BACKGROUND AND AIMS

Evidence for the association of total estradiol (E2) with cardiovascular disease (CVD) in young men is limited. We investigated the association of total E2 or free estradiol (FE2) and CVD mortality in a nationally representative multiracial sample of young and middle-aged men in the United States.

METHODS

Data were from 954 men without CVD, cancer, diabetes and not on androgen therapy or taking anabolic steroids, who participated in the National Health and Nutrition Examination Survey (1988-1991), for whom E2 was measured, and were followed for mortality through to 2015. Fasting serum levels of E2 were measured using competitive electrochemiluminescence immunoassays. Free estradiol was estimated from the levels of estradiol, sex hormone binding globulin, and albumin. International Classification of Diseases codes were used to define CVD mortality. Cox regression models were used to calculate hazard ratios (HR) and 95% confidence intervals (CI).

RESULTS

The average age of participants at baseline was 35.7 ± 11.6 years, with 11% and 6% reporting Black and Hispanic race and ethnicity, respectively. During a median follow-up of 25.2 years, 40 CVD deaths were recorded. Controlling for baseline demographic and CVD risk factors, and total testosterone levels, a 1 standard deviation decrement in log E2 (HR: 2.33, 95%CI: 1.11-5.00) or FE2 (HR: 1.89, 95%CI: 1.01-3.57) was associated with elevated risk of CVD mortality. This elevated risk was largely limited to non-Hispanic White men.

CONCLUSIONS

In this study, low levels of E2 or FE2 were associated with elevated risk of CVD mortality.

Testosterone level in men with type 2 diabetes mellitus and related metabolic effects: A review of current evidence

A significant proportion of patients with type 2 diabetes mellitus have a low testosterone level relative to reference ranges based on healthy young men. Only a small number of these patients suffer from classical hypogonadism as a result of recognizable hypothalamic-pituitary-gonadal axis pathology. The cut-off value of the serum testosterone level in men without obvious hypothalamic-pituitary-gonadal axis pathology is controversial. It is unclear to what extent a low serum testosterone level causally leads to type 2 diabetes and/or the metabolic syndrome. From a theoretical standpoint, there can be complex interactions among the hypothalamic-pituitary-gonadal axis, body composition and insulin resistance, which can be further influenced by intrinsic and extrinsic factors to give rise to metabolic syndrome, glucose intolerance, and low-grade inflammation to increase the risk of cardiovascular disease. Although a low serum testosterone level frequently coexists with cardiometabolic risk factors and might serve as a biomarker, more studies are required to clarify the causal, mediating or modifying roles of low serum testosterone level in the development of adverse clinical outcomes. Currently, there are insufficient randomized clinical trial data to evaluate the effects of testosterone replacement therapy on meaningful clinical outcomes. The risk-to-benefit ratio of testosterone therapy in high-risk subjects, such as those with type 2 diabetes, also requires elucidation. The present article aims to review the current evidence on low serum testosterone levels in patients with type 2 diabetes, and its implications on cardiovascular risk factors, metabolic syndrome and adverse clinical outcomes.

Reproductive parameters in young men living in Rochester, New York

OBJECTIVE

To describe semen quality and reproductive hormone concentrations of young men living in Rochester, New York, and to compare these with published data from similar European and Japanese populations.

DESIGN

Cross-sectional study.

SETTING

University and college campuses in the Rochester, New York, area.

PATIENT(S)

Unselected young college students (n = 222).

INTERVENTION(S)

A physical examination, blood and semen samples, and completion of a brief questionnaire.

MAIN OUTCOME MEASURE(S)

Semen parameters and serum reproductive hormone levels.

RESULT(S)

Subjects were aged 18-22 years (median age, 19.5 years), predominantly Caucasian (81%), and nonsmokers (79%), with a mean (SD) body mass index of 25.5 (4.2) kg/m(2). Overall, median sperm concentration was 52 × 10(6)/mL (5th-95th percentiles: 7-181 × 10(6)/mL), median total sperm count was 158 × 10(6) (14-587 × 10(6)), and 23.1% and 15.8% of men had a sperm concentration below 20 × 10(6)/mL and 15 × 10(6)/mL, respectively. Few men had serum hormones falling outside clinically normal ranges. Median sperm concentrations and reproductive hormone levels were comparable to those seen in young men in Denmark, Finland, and Japan.

CONCLUSION(S)

Our study provides the first data in 70 years on semen quality and reproductive hormones in young men in the United States with unknown fertility. These data suggest that, overall, reproductive parameters in our study population of young college students from the northeastern United States are similar to those of young European and Japanese men.

Genome-wide association studies on serum sex steroid levels

Even though the levels of circulating sex steroid hormones are to a large extent heritable, their genetic determinants are largely unknown. With the advent of genome-wide association studies (GWAS), much progress has been made and several genetic loci have been identified to be associated with serum levels of dehydroepiandrosterone sulfate, testosterone and sex hormone-binding globulin. The variants identified so far only explain a small amount of the overall heritability, but may help to elucidate the role of sex steroid hormones in common disorders such as hypogonadism, type 2 diabetes and hormone-sensitive cancers. This review provides an overview of the current state of knowledge of the genetic determinants of sex steroid hormones, with a focus on recent GWAS and brief directions for elucidating the remaining heritability.

Racial/ethnic differences in sex hormone levels among postmenopausal women in the diabetes prevention program

CONTEXT

Sex hormones may differ by race/ethnicity in postmenopausal women. Whether racial/ethnic differences also exist among those who are overweight and glucose intolerant is not clear.

OBJECTIVES

The objective of the study was to compare sex hormones by race/ethnicity [non-Hispanic white (NHW), Hispanic, African-American (AA)] in overweight, glucose-intolerant, postmenopausal women.

DESIGN

This was a secondary analysis of a randomized controlled trial.

PARTICIPANTS

Participants included postmenopausal glucose-intolerant women participating in the Diabetes Prevention Program.

INTERVENTIONS

Interventions included intensive lifestyle modification (consisting of diet and physical activity) or metformin 850 mg twice a day vs. placebo.

MAIN OUTCOME MEASURES

Baseline levels and 1-yr intervention-related changes in SHBG, total and bioavailable estradiol (E2), total and bioavailable testosterone, and dehydroepiandrosterone were measured.

RESULTS

At baseline, among women not using estrogen (n = 370), NHW had higher total and bioavailable E2 and testosterone levels than Hispanics independent of age, type of menopause, waist circumference, alcohol intake, and current smoking. NHW also had higher levels of bioavailable E2 and lower levels of SHBG than AA. At baseline, among estrogen users (n = 310), NHW had higher total and bioavailable E2 than Hispanics and higher levels of SHBG than AA after adjustment. At 1 yr, among women not using estrogen, NHW had larger declines in total E2 and bioavailable E2 levels than AA after adjustment for the above covariates, changes in waist circumference, and randomization arm. At 1 yr, among estrogen users, sex hormone changes did not differ by race/ethnicity.

CONCLUSIONS

Among postmenopausal women, there were significant race/ethnicity differences in baseline sex hormones and changes in sex hormones.

Associations between urinary metabolites of di(2-ethylhexyl) phthalate and reproductive hormones in fertile men

Widely used man-made chemicals, including phthalates, can induce hormonal alterations through a variety of cellular and molecular mechanisms. A number of rodent and observational studies have consistently demonstrated the anti-androgenic effect of several phthalates. However, there are only limited data on the relationship between exposure to these chemicals and reproductive hormone levels in men. All men (n=425) were partners of pregnant women who participated in the Study for Future Families in five US cities and provided urine and serum samples on the same day. Eleven phthalate metabolites were measured in urine and serum samples were analysed for reproductive hormones, including follicle-stimulating hormone, luteinizing hormone, testosterone, inhibin B and oestradiol and sex hormone-binding globulin (SHBG). Pearson correlations and parametric tests were used for unadjusted analyses, and multiple linear regression analysis was performed controlling for appropriate covariates. We observed weak or no associations with urinary phthalates other than di(2-ethylhexyl) phthalate (DEHP). All measures of testosterone [total, calculated free testosterone and the free androgen index (FAI)] were inversely correlated with the urinary concentrations of four DEHP metabolites. After adjustment by appropriate covariates, there was no longer an association between urinary DEHP metabolite concentrations and total testosterone levels; however, FAI was significantly associated with the urinary concentrations of several DEHP metabolites. SHBG was positively related to the urinary concentrations of mono(2-ethylhexyl) phthalate, but not with other DEHP metabolites, an association that was attenuated after adjustment. Our results suggest that DEHP exposure of fertile men is associated with minor alterations of markers of free testosterone.

Evidence for geographical and racial variation in serum sex steroid levels in older men

BACKGROUND

Despite considerable racial and geographical differences in human phenotypes and in the incidence of diseases that may be associated with sex steroid action, there are few data concerning variation in sex steroid levels among populations. We designed an international study to determine the degree to which geography and race influence sex steroid levels in older men.

METHODS

Using mass spectrometry, concentrations of serum androgens, estrogens, and sex steroid precursors/metabolites were measured in 5003 older men from five countries. SHBG levels were assessed using radioimmunoassay.

RESULTS

There was substantial geographical variation in the levels of sex steroids, precursors, and metabolites, as well as SHBG. For instance, Asian men in Hong Kong and Japan, but not in the United States, had levels of total testosterone approximately 20% higher than in other groups. Even greater variation was present in levels of estradiol, SHBG, and dihydrotestosterone. Group differences in body mass index did not explain most geographical differences. In addition, body mass index-independent racial differences were present; Black men had higher levels of estrogens (estradiol, estrone), and Asian men had lower levels of glucuronidated androgen metabolites.

CONCLUSIONS

On a global scale, there are important geographical and racial differences in the concentrations of serum sex steroids and SHBG in older men.

Are environmental levels of bisphenol a associated with reproductive function in fertile men?

BACKGROUND

Rodent and in vitro studies have demonstrated the estrogenicity of bisphenol A (BPA). However, few studies have examined the relationship between human exposure to BPA and male reproductive function.

OBJECTIVES

We investigated the relationships between environmental BPA exposure and reproductive parameters, including semen quality and male reproductive hormones, in prospectively recruited fertile men.

METHODS

Participants (n = 375) were partners of pregnant women who participated in the Study for Future Families in four U.S. cities, and all of the men provided blood, semen, and urine samples. BPA was measured in urine. Serum samples were analyzed for reproductive hormones, including follicle-stimulating hormone, luteinizing hormone (LH), testosterone, inhibin B, estradiol, and sex hormone-binding globulin (SHBG), as well as the free androgen index (FAI). Semen analyses were performed according to World Health Organization criteria. Pearson correlations were used for unadjusted analyses, and multiple linear regression analyses were used to examine associations controlling for age, body mass index, smoking, ethnicity, urinary creatinine concentration, time of sample collection, and duration of abstinence.

RESULTS

After multivariate adjustment, we observed no significant associations between any semen parameter and urinary BPA concentration. However, a significant inverse association was found between urinary BPA concentration and FAI levels and the FAI/LH ratio, as well as a significant positive association between BPA and SHBG.

CONCLUSIONS

Our results suggest that, in fertile men, exposure to low environmental levels of BPA may be associated with a modest reduction in markers of free testosterone, but any effects on reproductive function are likely to be small, and of uncertain clinical significance.

Association of endogenous sex hormones with diabetes and impaired fasting glucose in men: multi-ethnic study of atherosclerosis

OBJECTIVE

To assess associations of sex hormones with impaired fasting glucose (IFG) and type 2 diabetes in men.

RESEARCH DESIGN AND METHODS

A total of 3,156 African American, Non-Hispanic white, Hispanic, and Chinese-American men aged 45-84 years who participated in the baseline visit of the Multi-Ethnic Study of Atherosclerosis (MESA) were included. Odd sratios and 95% CIs for type 2 diabetes and IFG compared with normal fasting glucose for quartiles of hormones were estimated.

RESULTS

After adjusting for age, ethnicity, BMI, and waist circumference, IFG and diabetes were associated inversely with total testosterone and sex hormone-binding globulin (SHBG) and positively with estradiol (E2). Dehydroepiandrosterone was positively associated with IFG but not with diabetes. Associations did not differ across ethnic groups.

CONCLUSIONS

Regardless of obesity, total testosterone and SHBG were associated inversely and E2 was associated positively with IFG and diabetes in men. Further research is warranted to better understand the underlying biological mechanisms.

Research methodology: endocrinologic measurements in exercise science and sports medicine

OBJECTIVE

To provide background information on methodologic factors that influence and add variance to endocrine outcome measurements. Our intent is to aid and improve the quality of exercise science and sports medicine research endeavors of investigators inexperienced in endocrinology.

BACKGROUND

Numerous methodologic factors influence human endocrine (hormonal) measurements and, consequently, can dramatically compromise the accuracy and validity of exercise and sports medicine research. These factors can be categorized into those that are biologic and those that are procedural-analytic in nature.

RECOMMENDATIONS

Researchers should design their studies to monitor, control, and adjust for the biologic and procedural-analytic factors discussed within this paper. By doing so, they will find less variance in their hormonal outcomes and thereby will increase the validity of their physiologic data. These actions can assist the researcher in the interpretation and understanding of endocrine data and, in turn, make their research more scientifically sound.