[Gynecomastia and chronic renal insufficiency in periodic hemodialysis. Demonstration of a decrease in the free fraction of testosterone].

Gynecomastia is frequently observed in male patients undergoing hemodialysis; however, its mechanism is still unclear. Hormonal studies were performed in a group of 39 men, aged 50 +/- 14 years, dialysed for 2.8 +/- 2 years. 23 (59 p. 100) of them had gynecomastia. Peripheral hypogonadism and hyperprolactinemia were found in all the hemodialysed patients. Whether gynecomastia was present or not, no significant difference was observed for gonadotropins, prolactin, testosterone, estradiol 17 beta and testosterone-estradiol binding globulin levels. In contrast, the urinary output (p less than 0,05) and free testosterone (p less than 0,05) were significantly lower in the group with gynecomastia. Gynecomastia occurring in hemodialysed patients is probably due to a decrease of the testosterone/estrogen ratio. If so, percutaneous treatment with 5 alpha dihydrotestosterone might improve this type of gynecomastia.