The i.v. bolus administration of 1 alpha hydroxylated
vitamin D derivatives is effective in the treatment of uremic
hyperparathyroidism. However, few of the published studies of this mode of treatment have been adequately controlled, and recent reports have suggested that p.o. bolus administration may be just as effective. In this study, 16
hemodialysis patients with mild to moderate
hyperparathyroidism were assigned, after a 4-wk run-in period, to receive a 6-wk course of either thrice-weekly i.v. or p.o.
alfacalcidol (initial dose, 4 micrograms). Then, after a further control period, they received a second 6-wk course, with either p.o. or i.v.
alfacalcidol (whichever was not given in the first treatment period). Plasma
parathyroid hormone (PTH) was measured weekly by the use of an intact
hormone assay. Both routes of
therapy resulted in 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 between the increment in
calcium and the decrement in PTH. The most complete suppression of PTH was seen in those with the greatest increment in plasma
calcium. The incidence of
hypercalcemia and the mean
dose reductions necessary were also similar in the two treatment phases. Oral bolus
therapy and i.v. bolus
therapy with
alfacalcidol are equally effective in suppressing
hyperparathyroidism. The postulated advantages of i.v. over p.o.
therapy with 1 alpha hydroxylated
vitamin D derivatives remain to be confirmed by controlled studies.