Persistent hypophosphataemia and osteomalacia in dialysis patients not on oral phosphate-binders: Response to dihydrotachysterol therapy.

Four patients who had been on regular haemodialysis for periods of 3 1/2 to 7 years became hypophosphataemic with plasma-phosphate concentrations of 2.5 mg/dl or less before dialysis. None of them had been taking oral phosphate-binders for 2 years or more. Histologically all the patients had an excess of osteoid on bone biopsy. Intestinal absorption of phosphate and calcium was impaired, despite normal or high serum-25-hydroxycholecaliferol concentrations. Treatment with oral dihydrotachysterol resulted in corrections of the phosphate malabsorption and increases in plasma-phosphate concentration. The initial low plasma-phosphate values in these patients before dialysis probably reflected a state of phosphate depletion caused by the combination of malabsorption, loss during dialysis, and a low dietary intake.