Frequent recurrence of secondary hyperparathyroidism after pulse oral calcitriol withdrawal in PD patients.

The aim of this study was to evaluate the role of pulse oral calcitriol in the control of secondary hyperparathyroidism in peritoneal dialysis (PD) patients, addressing the effects after withdrawal. We studied 15 patients with intact parathyroid hormone (iPTH) plasma levels above 250 pg/mL. The initial calcitriol dose was 8 or 4 micrograms/week, administered in two doses, according to whether the iPTH plasma levels were above or below 400 pg/mL. This dose was modified during the follow-up according to the response. Serum iPTH levels decreased in all patients after the first month (559 +/- 243 to 212 +/- 94 pg/mL, p < 0.001). Serum calcium levels significantly increased during therapy, while serum phosphorus levels did not change. The mean duration of the treatment was 95 +/- 57 days. Nine patients reached the target iPTH levels without complications, and in 6 patients the treatment was interrupted because of hypercalcemia. One month after finishing pulse therapy, a significant decrease in serum calcium levels and an increase in iPTH levels were observed. These values were similar to baseline data and were significantly higher than those found during the pulse calcitriol period. Pulse oral calcitriol administration seems to be a short-term, efficient therapy for secondary hyper-parathyroidism in PD patients. However, after the end of pulse therapy, iPTH serum levels return to baseline values, suggesting long-term therapeutic failure.