Defective calcium absorption in the proximal small intestine in chronic renal failure: effect of dihydrotachysterol.

Intestinal absorption of calcium was evaluated in 6 uraemic patients and in 7 control subjects by a two isotope technique exploring absorption in the four hours following ingestion of the dose. In the first two hours, calcium absorption in the patients was markedly lower than normal and was corrected by 6-10 day administration of dihydrotachysterol, 0.66 mg per day. The administration of 0.33 mg per day proved less effective. The data indicate the existence of impaired intestinal calcium absorption in chronic renal failure and reversal of the defect after DHT administration. The method of investigation appears to be a valid procedure for the study of calcium malabsorption of CRF and in the evaluation of the effect of vitamin D metabolities and analogs.