Implications of intermittent calcitriol therapy on growth and secondary hyperparathyroidism

Secondary hyperparathyroidism is the most common skeletal lesion in pediatr ic patients undergoing maintenance dialysis. The present review summarizes a prospective randomized study that evaluated the biochemical and skeletal responses to intermittent calcitriol therapy in 33 pediatric patients on pe ritoneal dialysis with secondary hyperparathyroidism. Also, the effect of i ntermittent calcitriol therapy on linear growth was evaluated in 16 of 33 p atients who had completed the clinical trial. Serum parathyroid hormone lev els decreased by 62% from 648+/-125 pg/ml in patients treated with intermit tent intraperitoneal (IP) calcitriol, and values remained unchanged from pr e-treatment levels of 670+/-97 pg/ml with oral calcitriol therapy. Overall serum total and ionized calcium levels were higher in patients treated with IP calcitriol during the study. In contrast to these biochemical findings, the skeletal lesions of secondary hyperparathyroidism improved after 12 mo nths of treatment in both groups and adynamic bone occurred in 33% of the p atients. Z-scores for height decreased from -1.80+/-0.3 to -2.00+/-0.3, P<0 .01, after 12 months of intermittent calcitriol therapy. Such findings sugg est that an intermittent schedule of calcitriol administration adversely af fects chondrocyte activity within epiphyseal cartilage in pre-pubertal chil dren with end-stage renal disease.