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

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Abstract
The response of plasma testosterone (T), Δ4-androstenedione, and cortisol (F) to the administration of synthetic Zn βl-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 Δ4-androstenedione and F was observed (P < 0.0001), whereas the response of T showed a sex difference: T levels increased in females (p < 0.001) at all ages in response to ACTH, while they decreased (P < 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 percentages of the control levels, were significantly lower (P < 0.01) in infants (31.7 ± 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 μg/dl) than at any later age studied (64 ± 17 μ/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.