The effect of 5,6-trans-25-hydroxycholecalciferol in relative vitamin D resistancy.

The relative vitamin D resistance in patients with chronic renal failure and in those with hypoparathyroidism is due to an impairment of 1-hydroxylation of cholecalciferol. 5,6-trans-25OHCC, which has a similar steric configuration as 1,25(OH)2CC was examined at a daily dose of 18,000 IU fro 14 days in both diseases. Intestinal 47calcium absorption as well as serum calcium level could be normalized in most patients with hypoparathyroidism. The improvement was less in patients with chronic renal failure, suggesting an additional depressing influence of uremia on calcium metabolism.