Evaluation of testicular function in prepubertal boys by means of the luteinizing hormone-releasing hormone test.

Luteinizing hormone (LH)-releasing hormone (LH-RH) tests (50 microgram/sq m intravenously) were performed in 112 prepubertal boys ages 13/12 to 11 years (mean +/- standard deviation, 75/12 +/- 16/12 years) suspected of having a testicular disorder because of improperly located testes (77 boys) or hypogonadism (35 boys). Four of the patients were retested within a period ranging from 6 to 16 months. Of the 112 boys tested, 17% were found to have high basal levels of follicle-stimulating hormone (FSH) and 23% were found to have an abnormally high release of FSH after LH-RH administration. Only three patients had abnormally high basal levels of LH and/or elevated LH responses to LH-RH. The basal plasma testosterone levels were found to be normal in all 112 bosy. The fact that plasma FSH levels were elevated more often than LH levels suggests that the tubular elements are damaged more frequently than are the Leydig cells. The surprisingly high incidence of an abnormal response of plasma FSH to LH-RH in boys with mobile testes calls for an increased awareness of the importance of regular examination of these patients until full puberty has been achieved. It is concluded that determination of basal plasma FSH levels and the response to LH-RH stimulation is a useful diagnostic tool for evaluating testicular function in prepubertal boys with suspected pathology of the testes.