Racial differences in the association between sex hormone-binding globulin and adiposity in premenopausal women: The biocycle study

OBJECTIVE- To assess the associations between measures of adiposity and sex hormone-binding globulin (SHBG) and to evaluate whether such associations differ by race. RESEARCH DESIGN AND METHODS- Adiposity was measured by anthropometry and dual-energy X-ray absorptiometry among women (146 white, 50 black, and 25 Asian) aged 18-44 years in the BioCycle study. SHBG was repeatedly measured over one to two menstrual cycles. The ratio of trunkal to leg fat (T/L) was used to assess upper to lower body adiposity. RESULTS- Among whites, all adiposity measures were significantly and inversely associated with SHBG. Among blacks, BMI (β = -0.032), waist circumference (β = -0.016), and T/L (β = -0.033) were significantly associated with SHBG, whereas total and trunkal fat were not (P interaction with race <0.04). Among Asians, measures of central and upper body fat were significantly associated with SHBG (e.g., T/L, β = -0.84) but not BMI. CONCLUSIONS- Associations between SHBG and adiposity differ by race among premenopausal women.