[Comparative studies of calcium resorption modified by vitamin D2 and D3 in patients with chronic renal failure and dialysis patients].

In 16 patients with a chronic renal insufficiency at the stage of the compensated retention and 13 test persons of the chronic haemodialysis programme determinations of the total calcium and of the ionized calcium fraction as well as investigation of the intestinal calcium absorption by means of the isotope 47Ca were performed. In these cases the influence of vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol) on these parameters of the calcium metabolism was compared. Under the treatment with vitamin D a normalization of the serum calcium levels concerning the total calcium concentration as well as with regard to the ionized calcium fraction was achieved; this effect took place parallel to the improvement of the intestinal calcium absorption. Vitamin D3, had a more favourable effect than vitamin D2. The necessary doses are below 40,000 U a day.