Hormonal Changes in Childhood and Puberty

Abstract

The functional ontogeny of the hypothalamic-pituitary-gonadal axis has particular features: functional development is not completed until puberty; furthermore, its activity is high during fetal and early postnatal life, followed by a functional quiescence of part of the axis during childhood, before full maturation occurs during puberty. In males, basal gonadotropin and androgen levels are useful markers during the first 3–6 months and in puberty, whereas basal AMH and inhibin B can be used as markers during all developmental stages. At puberty, the decline in AMH and the increase in inhibin B reflect Sertoli cell maturation induced by androgens and FSH. Serum inhibin B is an excellent biomarker of spermatogenesis. In females, gonadotropins remain high for the first 2 years of life. AMH is a marker of the ovarian reserve from childhood through adulthood. The rise in serum inhibin B levels during puberty reflects follicle development induced by FSH. Menstrual cycles are irregular and frequently anovulatory in the first 2 years after menarche. AMH barely changes throughout the cycle, whereas inhibin B is higher during the follicular phase and inhibin A during the luteal phase. The adrenal, growth, and thyroid axes show minor or no changes during postnatal development. Adrenal androgen production increases, usually before pubertal onset, in both sexes, whereas IGF-I increases during puberty. Insulin secretion shows a transient rise, in correlation with a period of increased insulin resistance during pubertal development.