[Calcium and phosphorus metabolism in patients on chronic intermittent haemodialysis with different calcium concentrations in the dialysate (author's transl)].

A study was carried out in 25 patients on chronic intermittent haemodialysis on the effect of increasing the dialysate calcium concentration from 1.5 to 1.75 mMol/l on calcium and phosphorus metabolism. In 16 patients the increase in the dialysate calcium resulted in a sufficiently large increase in the plasma Ca level to suppress the parathyroid glands. The calcium influx during dialysis in these patients was sufficient to abolish the effects of diminished calcium absorption from the intestine due to loss of endocrine renal function. The remaining 9 patients showed no suppression of parathyroid gland activity and could be separated into two different groups, one requiring calcium supplementation and the other group manifesting signs of autonomic hyperparathyroidism. The five patients showing a higher calcium requirement were started on active vitamin D metabolites. In the remaining 4 patients parathyroidectomy will probably be inevitable if progression of the clinical manifestations of hyperparathyroidism occurs. Close control of plasma phosphorus levels is mandatory to avoid an increase in the calcium phosphate product or the danger of hypophosphataemic osteomalacia.