Obesity and Related Metabolic Biomarkers and Its Association with Serum Levels of Estrogen in Pre-pubertal Chilean Girls

Purpose: Recent reports show that girls with higher body mass index (BMI) have an earlier puberty onset (thelarche). It has been suggested that earlier puberty is a consequence of higher levels of estrogen due to increased aromatization of androgens in adipose tissue. Thus, we aimed to assess the relation between serum levels of estrogen and excess weight (BMI >= 1SD) and central adiposity (>75th percentile for waist circumference) in prepubertal girls at age 7. Materials and Methods: We conducted a cross-sectional study within the Growth and Obesity Cohort Study of 1190 low-middle income children from Santiago, Chile. We selected a random sample of 107 prepubertal girls at age 7. A trained dietitian measured weight, height and waist circumference. Additionally, a fasting blood sample was collected to measure serum levels of estradiol equivalents (via ultrasensitive recombinant cell bioassay), dehydroepiandrosterone sulfate (DHEAS), insulin, insulin-like growth factor 1 (IGF-1), and leptin. Results: Excess weight was observed in 40% of our sample; 11.2% had high central adiposity, and the mean level of estradiol equivalents was 3.6 +/- 2.3 pg/ml. In the univariate and multivariate analyzes, we did not observe an association between excess weight, central adiposity and estradiol equivalent levels; however, insulin was inversely associated with the serum level of estradiol equivalents. Conclusions: Our participants had a mean level of estradiol equivalents of 3.6 pg/ml (+/- 2.3 pg/ml) at the pre-pubertal stage. However, with the exception of insulin, we did not observe an association between estradiol equivalents and markers of adiposity and metabolic and hormonal factors.