'High-dose' calcitriol for control of renal osteodystrophy in children on CAPD

Abstract

High doses of calcitriol were used prospectively for 11 to 29 months to raise serum calcium levels in an effort to control renal osteodystrophy in 16 children undergoing CAPD. Serum Ca, P, iPTH and alkaline phosphatase were measured monthly; hand radiographs were obtained every six months, and a semiquantitative score of bone abnormalities was evaluated by two independent observers. During the study, serum Ca increased from 9.9 ± 0.9 to 11.0 ± 0.6 mg/dl (P < 0.001); serum iPTH decreased by 113 ± 131 μlEq/ml (P < 0.005); serum P was unchanged; and serum alkaline phosphatase fell by 33 ± 46% (P < 0.02), 530 ± 397 to 204 ± 551 IU/liter. The radiographic score fell from 4.8 ± 4.6 to 0.9 ± 1.2 (P < 0.005). The average and maximal doses of calcitriol were 0.61 ± 0.37 and 0.95 ± 0.56 μg/day or 28 ± 18 and 46 ± 28 ng/kg body wt/day, respectively. Transient and asymptomatic hypercalcemia occurred in nine patients and two patients had reversible conjunctivitis in association with the hypercalcemia. Thus, 'high dose' calcitriol prevented or controlled progression of hyperparathyroid bone disease in most pediatric CAPD patients. The failure to suppress PTH or reverse secondary hyperparathyroidism until the serum Ca rose to 10.5 to 11.0 mg/dl could reflect an increase in the 'set point' for PTH suppression by serum clacium in many uremic children.