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Earlier Puberty in Girls, or Earlier Pubertal Changes? The Hormone Story

      Background

      Recent studies have noted earlier onset of pubertal changes in girls. Earlier studies have noted increases in adrenal hormones prior to increases in the sex steroids in the peripubertal period. It is unclear if or how these events are related to each other, except through this temporal relationship.

      Methods

      Longitudinal observation study, conducted between the years 2004-2011. Participants were recruited between ages 6 and 7, and seen every six months. Trained and certified female examiners evaluated height, weight, and maturation status, and a fasting blood specimen was collected. Serum was analyzed for selected hormones every six months, beginning 30 months prior to, and extending to 6 months after, breast development. Androstenedione, estradiol, estrone, and testosterone serum concentrations were measured by high performance liquid chromatography (HPLC) with tandem mass spectrometry. Dehydroepiandrosterone-sulfate (DHEAS) and sex hormone binding globulin (SHBG) were also measured.

      Results

      There were 252 girls included in the analyses. Serum concentrations of DHEAS rose 24 months before breast development; androstenedione and estrone between 12 to 18 months before breast development; whereas estradiol and testosterone rose, and SHBG fell between 6 to 12 months before breast development. Girls with greater body mass index had lower concentrations of estradiol at onset of breast development as well as six months after pubertal onset.

      Conclusions

      The rise in serum estrone and DHEAS concentrations occurred prior to serum estradiol concentrations, and the rise in serum estradiol occurred prior to breast development. Similar to postmenopausal women, peripubertal girls appear to have peripheral conversion of adrenal androgens to estrone prior to pubertal onset, which could account for earlier age of pubertal changes without earlier activation of the hypothalamic-pituitary-ovarian axis. An additional mechanism would be the exposure to a class of endocrine disrupting chemicals called obesogens, resulting in an increase in adipocyte number and/or adipocyte dysregulation.