High-dose oral calcitriol and zero calcium peritoneal solutions in CAPD patients with refractory secondary hyperparathyroidism

Abstract. We evaluated the effect of pulse oral calcitriol (4µg three times weekly for 6 months) on parathyroid functionin nine CAPD patients with hyperparathyroidism refractory toconventional lowdose oral calcitriol. Zero calcium peritonealsolutions were used to prevent the development of hypercalcaemia.The peritoneal loss of calcium increased from 168á40to 417á48 mg/day using zero calcium solutions. Pulseoral calcitriol resulted in a significant decrease in PTH (from617á272 to 382á299 pg/ml) by the 15th day of therapy,while serum iCa did not change from baseline. During the firstmonth of therapy the mean PTH levels remained significantlyreduced compared to baseline, thereafter PTH increased in fourof nine patients. Hyperphosphataemia was not satisfactorilycontrolled in four patients, despite large amounts of bindersused; seven of nine patients developed hypercalcaemia and requiredeither the substitution of calcium acetate for calcium carbonateor reduction of calcitriol dose. Three patients showed a progressiveincrease in PTH. In conclusion our data suggest that in mostCAPD patients with severe hyperparathyroidism oral calcitriolpulse therapy is not effective in maintaining a permanent suppressionin PTH levels.