The plasma concentrations of dehydroepiandrosterone, androstenedione, and dehydroepiandrosterone sulfate decrease during the first year of life, remain low during childhood, and then increase during adrenarche. To determine whether alterations in adrenal enzyme activity might explain the changing secretory pattern of the adrenal androgens, we measured human adrenal microsomal 3β-hydroxysteroid dehydrogenase-isomerase, 17,20-desmolase, 17-hydroxylase, and 21-hydroxylase activities. Twelve adrenals from individuals aged 3 mo to 60 yr were studied. The patients were divided into 3 groups based upon the age of the patient when the adrenal glands were obtained: group 1, infants aged 3-8 mo (n = 3); group 2, preadrenarchal or early adrenarchal children aged 2-9 yr (n = 4); and group 3, adults aged 20-60 yr (n = 5). The mean activity of the 17,20-desmolase, 17-hydroxylase, and 21-hydroxylase fell by 50% and that of 3β-hydroxysteroid dehydrogenase-isomerase activity rose 80% from group 1 to group 2. A 4-fold increase in 17,20-desmolase (P < 0.002) and 17-hydroxylase (P < 0.001) activity and a doubling in 21-hydroxylase activity (P < 0.005) occurred between groups 2 and 3. We conclude that the decline in plasma adrenal androgens after birth appears to be associated with a rise in 3β-hydroxysteroid dehydrogenase-isomerase and a fall in 17,20-desmolase and 17-hydroxylase activity. The subsequent increase in plasma adrenal androgen concentration during adrenarche is coincident with a rise in 17,20-desmolase and 17-hydroxylase activity.
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