The effect of growth hormone on the Leydig cell response to chorionic gonadotrophin in boys with hypopituitarism.

Eleven boys with growth hormone (hGH) deficiency received human chorionic gonadotrophin (hCG) stimulation tests for the assessment of Leydig cell function before, during, and after 1 year of treatment with somatotrophin. Two patients entered puberty during the course of the study protocol. Analysis of the data in nine prepubertal boys revealed an augmentation of testosterone (T) responses to hCG in the presence of hGH. In six of these individuals in whom dihydrotestosterone (DHT) was determined, a similar augmentation in responsiveness of this steroid was found in the presence of hGH. Three prepubertal boys exhibited poor T responses to the basal hCG test with only partial improvement following hGH. In man growth hormone may be an important permissive factor in Leydig cell activity during periods of changing testicular function such as occur in utero or during puberty.