Short-term recombinant human growth hormone therapy does not modify growth hormone, thyrotropin and prolactin responses to thyrotropin-releasing hormone in adult dialysis patients

Background. We recently have reported the first randomized, controlled study on the effects of short-term recombinant human growth hormone (rhGH) therapy on the nutritional status of a group of malnourished adult dialysis patients. In order to evaluate whether rhGH administration exerts any influence on GH, thyrotropin (TSH) and prolactin (PRL) responses to TSH-releasing hormone (TRH), we assessed these responses before and after rhGH therapy. Methods. GH, PRL and TSH responses to TRH before and 1 month after rhGH therapy in a group of adult dialysis patients were evaluated. Seventeen dialysis patients (11 on continuous ambulatory peritoneal dialysis/six on haemodialysis) were studied (rhGH group, n = 8; control group, n = 9). In the rhCH group, 0.2 IU/kg/day rhGH was administered subcutaneously. Each patient was tested with TRH (400 mu g bolus i.v.) on two separate occasions, just before and immediately after the treatment period. Results. rhGH treatment did not modify baseline serum GH concentrations (6.6+/-2.7 vs 4.1+/-1.1 mu g/l), paradoxical GH responses to TRH (six out of eight patients), GH peak (11.9+/-4.6 vs 11.2+/-5.3 mu g/l, NS) or area under the secretory curve of GH (GH AUC; 19.1+/-4.5 vs 12.1+/-3.1 mu g/h/l). Both basal PRL (35.5+/-7.1 vs 36.7+/-8.6 mu g/l) and TSH (2.3+/-1.1 vs 2.8+/-1.7 mU/l) concentrations, as well as their responses to TRH stimulation (PRL peak, 59.9+/-16.6 vs 59.5+/-11.8 mu g/l; TSH peak, 6.2+/-2.6 vs 7.1+/-3.9 mU/l), were also unaffected by rhGH therapy. Conclusion. These results suggest that short-term rhGH therapy does not significantly influence the magnitude of the somatotropic, lactotropic or thyrotropic response to TRH in adult dialysis patients. However, this finding has to be interpreted with caution due to the two different patient groups included in this study.