A COMPARISON OF ORAL AND INTRAVENOUS ALFACALCIDOL IN THE TREATMENT OFUREMIC HYPERPARATHYROIDISM

The i.v. bolus administration of Icr hydroxylated vitamin D derivative s is effective in the treatment of uremic hyperparathyroidism. However , few of the pub lished studies of this mode of treatment have been ad equately controlled, and recent reports have suggested that p.o. bolus administration may be just as effective. In this study, 16 hemodialys is patients with mild to moderate hyperparathyroidism were assigned, a fter a 4-wk run-in period, to receive a 6-wk course of either thrice-w eekly i.v. or p.o. alfacalcidol (initial dose, 4 mu g). Then, after a further control period, they received a second 6-wk course, with eithe r p.o. or i.v. alfacalcidol (whichever was not given in the first trea tment period). Plasma parathyroid hormone (PTH) was measured weekly by the use of an intact hormone assay. Both routes of therapy resulted i n a significant suppression of plasma PTH (P = 0.005) and an elevation in plasma ionized calcium (P = 0.01). The magnitude of the responses was similar for the two treatment phases, as was the relationship betw een the increment in calcium and the decrement in PTH. The most comple te suppression of PTH was seen in those with the greatest increment in plasma calcium. The incidence of hypercalcemia and the mean dose redu ctions necessary were also similar in the two treatment phases. Oral b olus therapy and i.v. bolus therapy with alfacalcidol are equally effe ctive in suppressing hyperparathyroidism. The postulated advantages of i.v. over p.o. therapy with la hydroxylated vitamin D derivatives rem ain to be confirmed by controlled studies.