1,25 Dihydroxy-Vitamin D₃ in Normal Man and Patients with Renal Failure

Abstract

The actions of 1,25 dihydroxy-vitamin D3 (1,25(OH)2D3), the most active form of vitamin D, were evaluated in 20 trials in 12 normal subjects and in 15 studies in 10 patients with advanced renal failure. The steroid was given orally, 0.027, 0.14, 0.68, and 2.7 µg/day (molar equivalent to 1, 5, 25, and 100 IU of vitamin D), for 7 to 16 days. In normal subjects, calcium absorption and urinary calcium increased after administration of 0.14 to 2.7 µg/day; 0.68 to 2.7 µxg/day augmented calcium absorption in the uremic patients. Fecal calcium fell significantly during metabolic balance studies. The marked action in normal subjects, compared with much larger doses of vitamin D3, emphasize the existence of regulation of the production of 1,25(OH)2D3 from its precursors. The steroid corrected the "vitamin D-resistance" of uremia, observations compatible with defective renal production of 1,25(OH)2D3 in uremia.