LIMITATIONS OF PULSE ORAL CALCITRIOL THERAPY IN CONTINUOUS AMBULATORYPERITONEAL-DIALYSIS PATIENTS

Calcitriol is increasingly used for therapy of secondary hyperparathyr oidism in patients with end-stage renal disease. Its therapeutic effic acy, however, often has been limited by the associated increase in int estinal calcium and phosphorus absorption. Previous studies reported t hat these side effects could be avoided by intermittent administration of calcitriol in high doses, subsequently referred to as pulse therap y. The present study was designed to investigate pulse oral calcitriol therapy in a patient subgroup especially susceptible to the developme nt of hypercalcemia and hyperphosphatemia under standard continuous ca lcitriol treatment. We examined 15 peritoneal dialysis patients with m oderate degrees of hyperparathyroidism (intact parathyroid hormone [iP TH] levels, 150 to 903 pg/mL) ingesting between 1.5 and 6 g of calcium salts as the sole phosphate binders. Treatment consisted of 0.5 mu g calcitriol twice weekly. Eight of these patients had been previously c onverted to low calcium dialysate to tolerate the necessary doses of p hosphate-binding calcium salts. During the study period, comprising 8 pretreatment weeks and 8 weeks of therapy, dialysates and doses of cal cium salts were not changed, so that only calcitriol influenced the de termined parameters. As expected, iPTH levels decreased rapidly in all patients (P < 0.0001). However, within 4 weeks of treatment a marked increase in calcium phosphorus products was observed (P < 0.0001). Ove rt hypercalcemia developed in five patients. We concluded that pulse o ral calcitriol has to be carefully monitored in peritoneal dialysis pa tients receiving high doses of calcium salts because of the increased risk for hypercalcemia and hyperphosphatemia. (C) 1995 by the National Kidney Foundation, Inc.