Effect of Parathyroidectomy on Serum la,25-Dihydroxyvitamin D and Intestinal Calcium Absorption in Primary Hyperparathyroidism*

Abstract

Serum concentration of lα,25-dihydroxyvitamin D [1,25(OH)₂D] and intestinal absorption were measured before and after parathyroidectomy in 11 patients with primary hyperparathyroidism. Serum 1,25(OH)₂D was high preoperatively (P < 0.001) and normal postoperatively. Ca absorption was elevated preoperatively (P < 0.001) and decreased significantly after parathyroidectomy (P < 0.001). However, 5 of 11 patients had a persistent hyperabsorption of Ca postoperatively, despite normal serum 1,25(OH)₂D. The results suggest that factors other than 1,25(OH)₂D contribute to the maintenance of high intestinal Ca absorption in hyperparathyroid patients in the postoperative state.