Associations Between Body Size and Serum Estradiol and Sex Hormone-Binding Globulin Levels in Premenopausal African American Women

Context: African American (AA) women have the highest rates of premenopausal breast cancer; however, it is unclear whether body size contributes to the hormonal patterns potentially associated with increased breast cancer risk in these women. Objective: To characterize the association between body size and serum levels of estradiol and sex hormone-binding globulin (SHBG) levels in a sample of premenopausal AA women. Design: A total of 164 premenopausal AA women who were not pregnant or breastfeeding were recruited for this study. Serum samples were collected during the early follicular phase, and trained staff collected body size measurements. Multiple linear regression models were performed to assess potential associations. Main Outcome Measures: Serum estradiol and SHBG levels. Results: Many (81%) of the women enrolled were overweight or obese. Both waist-to-hip ratio (WHR) (beta = 2.68, P = .008) and waist circumference (WC) (beta = 2.02, P = .046) were positively associated with higher levels of estradiol. All measures of body was significantly and inversely associated with SHBG levels (all P < .05). Conclusions: Premenopausal AA women with higher WHR or larger WC may have higher levels of estradiol and lower levels of SHBG. Thus, WHR or WC may be better indicators for assessing hormonal patterns implicated in breast cancer pathogenesis in these women. (J Clin Endocrinol Metab 98: E485-E490, 2013)