OBJECTIVESTo observe the change of erythropoietin (EPO) in patients of hypogonadism who received androgen replacement treatment and explore the mechanism of androgen-induced increase of red blood cells and haemoglobin.

METHODSEight patients with Klinefelter's syndrome, divided into two groups, received TU intramuscular injections of 500 mg or 1000 mg dose, respectively. After three months, seven patients received the second injection of crossover dose. Testosterone levels in serum were measured with RIA before and after the injections treatment. RBC count, impacted volume of blood cells and haemoglobin concentration were measured before treatment and 4, 8 weeks after treatment. At the same interval, EPO levels were measured with ELISA method.

RESULTSDevelopment of the secondary sex characters was improved in all patients after the TU injection. Serum testosterone levels raised significantly and reached the peak one week after the injections. Effective level of testosterone lasted for over 6 weeks. RBC count, impacted volume of blood cells and haemoglobin increased at different degrees after TU injections, but these changes were not significant in statistic(P < 0.05). The increased levels remained for 8 weeks. EPO levels were elevated significantly (P < 0.01 or 0.05) after the TU injection(Pbat > 0.05). The second injection could still make the EPO level go up.

CONCLUSIONSAndrogen replacement treatment can increase the EPO levels in patients of hypogonadism, which is one of the mechanism of RBC production increase.