COMPARATIVE EFFECT OF ORAL OR INTRAVENOUS CALCITRIOL ON SECONDARY HYPERPARATHYROIDISM IN CHRONIC-HEMODIALYSIS PATIENTS

The suppressive effects of intravenous (IVC) and oral (ORC) 1,25(OH)(2 )D-3 (calcitriol) therapies on parathyroid hormone (PTH) secretion wer e compared in 10 hemodialysis (HD) patients with secondary hyperparath yroidism (SHPT). These patients were randomized to receive either IVC or ORC therapy for 12 weeks, both followed by a 12-week washout period . After the washout, the patients who received IVC then switched to OR C therapy for another 12 weeks, and the patients who received ORC swit ched to IVC therapy. The mean dose of IVC was 2.45 +/- 0.30 mu g/dialy sis session (congruent to 1.05 mu g/day) and that of ORC was 0.69 +/- 0.07 mu g/day. A significant reduction in serum levels of intact PTH w as observed after 8 weeks and that of C-PTH after 10 weeks of ORC ther apy, but both fell after 6 weeks of IVC treatment. There was a concomi tant reduction in serum alkaline phosphatase (AP), but it became signi ficant 4 weeks later than in intact PTH. The maximal reductions of ser um levels of intact PTH, C-PTH and AP were 74.28, 64.91, 41.97%, respe ctively, after IVC, and 31.57, 24.39, 22.50%, respectively, after ORC therapy. Serum calcium rose faster during ORC treatment. There were no significant changes in serum levels of phosphorus, magnesium, and alb umin throughout the treatment period. We conclude that both IVC and OR C treatments result in a significant decrement in blood levels of PTH in chronic HD patients with SHPT. However, this PTH-suppressive effect is more pronounced with IVC therapy, and cannot be totally explained by either the higher dose or elevated serum calcium.