Age-Related Response of Plasma Testosterone, Δ4-Androstenedione, and Cortisol to Adrenocorticotropin in Infants, Children, and Adults*

Abstract

The response of plasma testosterone (T), delta 4-androstenedione, and cortisol (F) to the administration of synthetic Zn beta 1-24 ACTH (0.5 mg/m2 im every 12 h for 3 days) was ascertained in 20 infants, 35 prepubertal children, 4 early pubertal boys, and 15 adults. At all ages and in both sexes, a significant rise in delta 4-androstenedione and F was observed (P less than 0.00001), whereas the response of T showed a sex difference: T levels increased in females (P less than 0.001) at all ages in response to ACTH, while they decreased (P less than 0.01) in males at periods of active testicular secretion (early infancy, puberty, and adulthood). In prepubertal boys, in the absence of significant Leydig cell activity, T levels increased after ACTH, as they did in girls. The post-ACTH values of T, expressed as percent-ages of the control levels, were significantly lower (P less than 0.01) in infants (3.17 +/- 16.7%) than in pubertal boys (59.5 +/- 14.6%) or adult men (57.9 +/- 7.7%). F levels were significantly higher after ACTH stimulation at 1-4 months of age (253 +/- 129 micrograms/dl) than at any later age studied (64 +/- 17 micrograms/dl). It would seem, therefore, that the suppressive effect of ACTh on testicular secretion might be glucocorticoid mediated and its magnitude might be related to circulating levels of F.