A randomized trial of intermittent versus continuous oral alfacalcidol treatment of hyperparathyroidism in end-stage renal disease.

Background: Secondary hyperparathyroidism, a major clinical problem in patients with chronic renal failure, develops in response to phosphate retention and impaired calcitriol [1,25-dihydroxyvitamin D 3 ] synthesis. Vitamin D therapy, particularly alfacalcidol [ 1 alpha-hydroxyvitamin D 3 ], has been shown to be effective in the treatment of secondary hyperparathyroidism. The aim of this study was to compare the effect of a 12-week course of continuous versus intermittent oral alfacalcidol therapy on parathyroid hormone suppression. Patients and methods: 34 patients were selected and randomly divided into 2 groups to receive either intermittent or continuous oral alfacalcidol. Baseline data were obtained on serum calcium, phosphorus, alkaline phosphatase and PTH. All but the PTH were monitored monthly. PTH levels were measured again until the end of the protocol. The intervention was 2 μg of alfacalcidol given after each dialysis session (intermittent group) or 1 μg given 6 days/week (continuous group). Results: Serum calcium and phosphorus showed a tendency to increase from baseline levels in both groups. Mean PTH levels for both groups showed a progressive reduction over time during the study period. This decrement showed no significant difference with regard to the schedule of alfacalcidol administration when comparing the 2 groups. There also was no difference in the incidence of side effects -hypercalcemia and hyperphosphatemia - between the intermittent and continuous intervention. Conclusion: Feedback regulation of PTH with oral alfacalcidol therapy is efficient in the treatment of hyperparathyroidism. However, intermittent and continuous oral administration are equally effective in suppressing an elevated PTH level in hemodialysis patients, with similar safety margins.