Prepubertal Hormone Levels Differ Sharply Between Overweight, Normal-Weight Girls
Using new methods to determine hormone levels in prepubertal girls, a Cincinnati Children’s research team has demonstrated that significant changes in hormone levels can be detected prior to clinically evident changes in puberty – a finding that could help explain why breast cancer risks vary among obese and non-obese women later in life.
This longitudinal study examined relationships between adrenal and sex hormones in 252 peripubertal girls in Cincinnati who were recruited between 2004 and 2010. Participants entered the study between ages 6 and 7 and were followed from 30 months before to six months after the appearance of breast development. Detailed findings were published online July 16, 2014 in the Journal of Clinical Endocrinology & Metabolism.
“We noted radical differences between overweight and normal weight girls, and our data suggest that heavy girls are producing some of their circulating estrogens from their adipose tissue, rather than from their ovaries,” says Frank Biro, MD, first author of the study. “That finding is consistent with differing rates of breast cancer among postmenopausal women when comparing obese and non-obese.”
Gathering data on estradiol, estrone, androstenedione, and T serum concentrations required using high-performance liquid chromatography (HPLC) with tandem mass spectrometry, a newer and highly sensitive analytic approach. Dehydroepiandrosterone sulfate (DHEA-S) and SHBG were measured through established methods.
The research team reports that the average age of breast development in the study group was 8.78 years. Testing revealed that hormone concentrations of DHEA-S increased 30 to 18 months prior to breast development; androstenedione and estrone levels increased 12 and 18 months before onset of breast development; estradiol and T-serum concentrations increased while SHBG levels decreased six to 12 months before breast development.
Heavier peripubertal girls had lower estradiol levels at puberty. These findings suggest a mechanism, especially in heavier girls, for pubertal changes without activating the hypothalamic-pituitary-ovarian axis.
