Hypothalamo-hypophyseal thyroid and gonadal function before and after erythropoietin therapy in dialysis patients

We examined the effects of administration of two hypothalamic neurohormones, TRH and GnRH, for 3 days in five anemic male dialysis patients and five age-matched normal male volunteers. Patients on chronic hemodialysis have abnormal hypothalamo-hypophyseal thyroid and gonadal functions, including blunted TSH response to TRH, hyperprolactinemia, elevated basal levels of LH with exaggerated response to GnRH, and depressed FSH secretory response to GnRH. After correction of anemia with exogenous erythropoietin, these dialysis patients were given a single injection of the same hypothalamic hormones. The repeat studies after the correction of anemia showed normalization of 1) the TSH response to TRH, 2) basal GH and PRL levels, and 3) the FSH response to GnRH. Although these patients appear to have biochemical evidence of testicular failure, the gonadotropin response (FSH) to GnRH was not exaggerated. In addition, there was no increase in total T4 and free T4 after TRH administration. Although a free T3 response to TRH was present, it was remarkably blunted compared to that of controls. At the present time, it is not known whether these hormonal responses after the correction of anemia are due to better oxygenation or a trophic action of the erythropoietin.