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We measured serum reproductive hormone concentrations in a community-based, multiethnic population of premenopausal and early perimenopausal women to determine whether there are ethnic differences in hormones that can be explained by host factors. We studied 2930 participants in the Study of Women's Health Across the Nation who were aged 42-52 yr and self-identified as African-American (27.6%), Caucasian (47.1%), Chinese (7.4%), Hispanic (8.8%), or Japanese (9.0%) at 7 clinical sites. Outcome measures from this baseline assessment of a longitudinal study were serum estradiol (E2), FSH, testosterone (T), dehydroepiandrosterone sulfate, and SHBG concentrations and calculated estimates of free steroid availability, free testosterone index, and free E2 index from serum collected primarily in the early follicular phase of a spontaneous menstrual cycle. The primary explanatory variables were race/ethnicity, menopausal status, age, body mass index, day of the cycle, smoking, alcohol use, and physical activity. Chinese women had lower unadjusted E2 and SHBG levels, and Hispanic women had lower unadjusted T levels than other ethnic groups. Unadjusted serum FSH levels did not differ by race/ethnicity. E2 levels adjusted for host characteristics, particularly body size, did not differ by race/ethnicity. Adjusted FSH levels were higher, and adjusted T levels were lower in African-American and Hispanic women. Serum E2 and FSH concentrations were highly variable. Serum FSH levels, but no other hormone concentrations, were positively correlated with menopausal status. Serum dehydroepiandrosterone sulfate levels were negatively correlated with age, but not menopausal status. All hormone concentrations were significantly correlated with body mass index. We conclude that serum sex steroid, FSH, and SHBG levels vary by ethnicity, but are highly confounded by ethnic disparities in body size. to reproductive senescence in women is characterized by a progressive loss of ovarian response to pituitary stimulation as ovarian follicles lose the ability to develop, mature, and ovulate reproductively competent oocytes. Endocrinologically, this process of reproductive aging is characterized by a progressive rise in serum FSH levels associated with a decrease in serum estradiol (E2) levels (1), although current evidence suggests stage-specific variation in this general pattern (2). In contrast, serum dehydroepiandrosterone sulfate (DHEAS) levels decrease steadily with age without any known relationship to the loss of ovarian folliculogenesis (3, 4), leading to consideration of DHEAS as a marker of somatic aging. Once again, evidence is emerging that menopause stage-specific data are at variance with that pattern (5).No study, whether cross-sectional (6) or longitudinal (1,7,8), has investigated ethnic differences in reproductive hormones in midlife women. However, ethnic variation in hormone concentrations has been observed in menopausal women, as serum E2 levels are lower in Chinese women than in Caucasian women (9). In addition, host facto...

Age, health and lifestyle factors impact androgen levels and should be accounted for in calculations of normal reference ranges. We propose the following age-specific thresholds, below which a man is considered to have an abnormally low total T: 8.7, 7.5, 6.8 and 5.4 nm (251, 216, 196 and 156 ng/dl) for men in their 40s, 50s, 60s and 70s, respectively. These cutoffs correspond to the 2.5th percentile in our data; thus, approximately 2.5% of men aged 40-79 years would have abnormally low T levels based on hormone levels alone.