RESUMO
Twenty four-hour urine samples have been collected 6 monthly for 18 months from 127 normal boys aged between 7.5 and 17 years. Urinary steroid metabolites have been measured by gas-liquid chromatography and ratios of steroid metabolites used to draw conclusions about likely enzymic activities at each step in the adrenal biosynthetic pathway. DHA excretion rose throughout the study, especially between 7.5 and 11 years. Metabolites of cortisol and corticosterone did not increase when related to surface area. During adrenarche there were changes consistent with a decrease in 3 beta-hydroxysteroid dehydrogenase activity, a slight rise in 17 alpha hydroxylase activity, a marked rise in 17,20 lyase activity, and a fall in 11 beta hydroxylase activity. These data are compatible with the hypothesis that a small reduction in the ability to synthesize cortisol requires a marginal increase in the secretion of ACTH and/or other CRF-induced peptides to maintain cortisol production rate. ACTH itself or a dexamethasone-suppressible CRF-induced peptide would in such a case control the growth of the zona reticularis at adrenarche, which thus appears to be primarily an adrenal event.