Effect of Calcitriol in the Control of Plasma Calcium after Parathyroidectomy

Severe, prolonged hypocalcemia in observed in some, but not all, hemodialysis patients after parathyroidectomy performed because of uncontrolled hyperparathyroidism. The aim of the present study was to investigate whether calcitriol and calcium supplementation in the immediate period after parathyroidectomy (days 1-14) was of more help in the control of plasma calcium than calcium supplementation alone. Fourteen hemodialysis patients were enrolled in a prospective, randomized, double-blind and placebo-controlled study. From the day after parathyroidectomy, 7 patients received calcitriol and the remaining 7 a placebo using incremental doses adjusted to the degree of hypocalcemia (up to 4 micrograms/day for calcitriol). Plasma calcium, phosphorus, alkaline phosphatase and immunoreactive parathyroid hormone levels before parathyroidectomy were comparable in both patients groups, as was the lowest plasma calcium achieved after parathyroidectomy. The decrease in plasma calcium after parathyroidectomy was related to plasma alkaline phosphatase and to the number of osteoclasts and osteoblasts on bone biopsy surface before parathyroidectomy. The mean decrement of plasma calcium (days 3-9) as compared to that before parathyroidectomy was less pronounced in calcitriol-treated than in placebo-treated patients (0.25 +/- 0.06 versus 0.45 +/- 0.05 mM, mean +/- SEM, p less than 0.025). Treatment with placebo was interrupted before day 14 because of persistent severe hypocalcemia in 4 of 7 patients, whereas calcitriol treatment was continued in all 7 patients up to 14 days. Patients on calcitriol treatment required less mean calcium supplements (days 1-9) than patients receiving placebo (37.4 +/- 3.2 versus 49.4 +/- 3.7 g, p less than 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)