Abnormal prolactin secretion in prepubertal boys with hypogonadotrophic hypogonadism--possible involvement in regulation of testicular steroidogenesis.

The interrelationships of prolactin (Prl), gonadotrophins and testicular steroids were studied in prepuberty in 6 boys with isolated hypogonadotrophic hypogonadism (HH) and 7 boys with incomplete testicular descent (who served as controls). The boys with HH had higher basal serum levels of Prl (P less than 0.001) and LH (P less than 0.05) than the controls, but lower Prl (P less than 0.001) and LH (P less than 0.05) responses after metoclopramide + LHRH and lower testosterone responses after hCG. The peak responses of Prl after metoclopramide + LHRH and of testosterone after hCG correlated strongly in the patients as a whole (r = 0.87, P less than 0.001). These observations indicate that, as well as in the gonadotrophins, changes occur in HH in prepuberty in the synthesis and/or release of Prl. The findings also raise the possibility that Prl may play a role in the regulation of testosterone synthesis by the prepubertal testis.