LACK OF INFLUENCE OF RECOMBINANT-HUMAN-ERYTHROPOIETIN ON PARATHYROID FUNCTION IN HEMODIALYSIS-PATIENTS WITH SECONDARY HYPERPARATHYROIDISM

The effects of recombinant human erythropoietin (rHuEPO) treatment on parathyroid function in patients on maintenance hemodialysis (HD) with secondary hyperparathyroidism (HPT) is poorly understood. We compared the levels of serum intact parathyroid hormone (PTH) and the suppress ibility of PTH by intravenous calcium infusion before and after 12 wee ks of rHuEPO treatment in 8 HD patients with secondary HPT. The suppre ssibility of PTH by calcium infusion in HD patients was also compared with that of normal subjects. After rHuEPO treatment, in HD patients h ematocrit and hemoglobin levels increased significantly from 20.1 +/- 1.3% and 6.65 +/- 0.46 g/dl to 28.7 +/- 1.0% and 9.68 +/- 0.39 g/dl, r espectively. The serum intact PTH levels did not change significantly (541.9 +/- 65.3 pg/ml before versus 572.9 +/- 75.3 pg/ml after rHuEPO treatment), nor did serum ionized calcium, phosphate, magnesium, alumi num, alkaline phosphatase, and 1.25(OH)(2)D levels. Calcium infusion s ignificantly increased serum ionized calcium and suppressed serum PTH levels. However, the increment in serum calcium levels and the percent decrement of serum PTH showed no significant differences before and a fter rHuEPO treatment in HD patients. Elevations in serum calcium leve ls during calcium infusions were not significantly different between n ormal subjects and HD patients. However, the percent maximal decrement in serum PTH level was less in HD patients both before and after rHuE PO treatment than in normal subjects (-75.4 +/- 3.9 and -76.4 +/- 4.1% versus -91.4 +/- 1.4%). We conclude that rHuEPO treatment has no infl uence on parathyroid function in maintenance HD patients with secondar y HPT. In addition, PTH secretion is less suppressed by calcium infusi on in the same group of patients.