Hypercalcemia and Increases in Serum Hormone Value during Prolonged Administration of 1α,25-Dihydroxyvitamin D

Abstract

PREVIOUS studies have indicated that in pseudohypoparathyroidism there is a defect in the renal production of 1α,25-dihydroxyvitamin D. The mean concentration of the hormone in the circulation is abnormally low.^{1 , 2} We have reported in short-term studies that impaired intestinal absorption of calcium, hypocalcemia and secondary hyperparathyroidism can be corrected by small doses of 14α,25-dihydroxyvitamin D₃.^{1 , 3} We now describe some complications of the long-term use of 1α,25-dihydroxyvitamin D₃ in pseudohypoparathyroidism. We find that increases in serum 1α,25-dihydroxyvitamin D₃ may occur after its prolonged administration, and that these increases in hormone value are associated with hypercalcemia. The increased . . .