Adiposity and sex hormones in girls.

A202

Greater body fatness during childhood is associated with reduced risk of premenopausal breast cancer, but few studies have addressed the relation of adiposity with sex hormones in girls. We prospectively examined associations between adiposity at ages 8 to 10 and circulating levels of sex hormones and sex hormone-binding globulin (SHBG) during seven years of follow-up among 286 girls in the Dietary Intervention Study in Children. Anthropometric measurements were taken at baseline and at subsequent annual visits, and blood samples for hormone assays were collected approximately every two years, at baseline and at the year 1, year 3, year 5, and last visits. Hormone levels during follow-up were examined according to body mass index (BMI) at baseline, when participants were between ages 8 and 10. Concentrations of the adrenal androgen DHEAS during follow-up were higher among girls with greater BMI at baseline. The mean for the lowest BMI quartile was 63.0 ng/dL compared to 78.8 ng/dL for the highest quartile, and each kg/m² increment in baseline BMI was associated with a 4.3% difference (95% CI: 1.6% to 7.0%) in DHEAS levels during follow-up (P trend = 0.002). Concentrations of SHBG during follow-up were lower among girls with greater BMI at baseline. The mean for the lowest BMI quartile was 94.8 nmol compared to 57.5 nmol for the highest quartile, and each kg/m² increment in baseline BMI was associated with an 8.8% difference (95% CI: -7.0% to -10.6%) in SHBG levels during follow-up (P trend < 0.0001). Concentrations of estrogens and progesterone during follow-up were similar across quartiles of BMI at baseline. These findings suggest that adiposity at young ages may alter levels of DHEAS and SHBG in girls. Whether and how these differences possibly affect breast development and carcinogenesis requires further research.