Response to a single dose of human chorionic gonadotropin in prepubertal boys

In normal men a single dose of hCG induces an increase in plasma testosterone (T) and 17 alpha-hydroxyprogesterone (17 alpha-OHP) 2-4 h after the injection; after 24-36 h a maximum increase in plasma 17 beta-estradiol (E2) and 17 alpha-OHP occurs followed by a second surge in T after 48-96 h. The present investigation focuses on the effect of a single dose of hCG (3500 IU/m2 body surface) on testicular steroid production in 12 boys aged 13 months to 12 yr. Plasma hCG, 17 alpha-OHP, androstenedione (A), T, dihydrotestosterone, and E2 were measured basally and 2, 4, 24, 48, 72, and 96 h after hCG administration. Plasma hCG was measured using a double antibody RIA technique and steroids by RIA after celite chromatography. The results show that hCG peaked 2 h after administration of the hormone and high levels persisted for up until 72 h. Plasma T and dihydrotestosterone increased after 48 h and remained significantly high for another 48 h; 17 alpha-OHP, A, and E2 did not change. These findings show that hCG stimulation in prepubertal boys induces significant production of T without affecting the precursors or aromatization product, in contrast to observation in the adult man, where 17 alpha-OHP, A, and E2 increase significantly. A response comparable to that observed in children has been recorded in adult males with hypogonadotropic hypogonadism.