Prolactin, thymulin and zinc in chronic hemodialysis: effect of renal transplant

The interrelationships between PRL, thymulin and Zn, were studied in 25 patients with chronic renal failure (CRF) undergoing kidney transplantation and immunosuppressed with cyclosporine A (CsA). The possible role of serum PRL levels in predicting allograft rejection was also investigated. Before the kidney transplant serum PRL levels were significantly higher than in normals (mean ± SE, 28.3 ± 7.1 vs 7.5 ± 0.6 μ/l p < 0.001) and their response to TRH (200 μg iv) was impaired (mean Δ% at peak, 45.4 ± 9.5 vs + 641 ± 47.5, p < 0.001). After kidney transplantation a dramatic decrease in serum PRL concentrations was observed in all patients, followed by a slight upward trend in the following two weeks, while TRH test administered on 3rd, 7th and 14th day, induced a progressive increase in serum PRL responses (Δ% at peak, 201 ± 43.3, 220 ± 37.1 and 305 ± 15.5, respectively). No difference in serum PRL patterns was observed between patients with (8 cases) and without (17 cases) clinical features and kidney fine needle biopsies suggestive of rejection. Basal serum Zn levels of patients with CRF (18.1 ± 0.6 /gmmol/l) were similar to those observed in normals (17.7 ± 0.2 μmol/l) and without any correlation with serum PRL levels. A decrement in serum Zn was recorded during CsA infusion and on the first day after the surgery, followed by a sligth and slow upward trend. Basal serum thymulin titers were low [2.92 ± 0.18 (1/log2)], were further reduced after CsA infusion [1.68 ± 0.15 (1/log2)] and returned to the pre-transplant levels in the two weeks after grafting. In conclusion, a) the renal transplant induced a rapid normalization of serum PRL levels and a gradual improvement of TRH-stimulated PRL secretion, b) serum PRL levels were not predictive of kidney rejection, and c) no correlation was found between serum PRL and thymulin and Zn. © 1990, Italian Society of Endocrinology (SIE). All rights reserved.