PHOSPHATE AND lα‐HYDROXYVITAMIN D3 THERAPY IN HAEMODIALYSIS PATIENTS

Abstract

SUMMARYThirty‐nine adult patients on maintenance haemodialysis were treated with lα‐hydroxyvitamin D3 for 8 months. Twenty patients (Group I) were treated without concurrent aluminium hydroxide therapy, and nineteen patients (Group II) were given aluminium hydroxide to achieve a pre‐dialysis plasma phosphate of 1.60mmol/l or less.There was malabsorption of calcium and phosphorus in both groups. The radio‐calcium absorption in Group II did not increase after reduction of plasma phosphate with aluminium hydroxide. In Group I higher doses of lα‐hydroxyvitamin D3 were required as compared to Group II to increase calcium absorption to normal without causing hypercalcaemia above 3 mmol/l.The plasma calcium increased from a mean value of 2.65 mmol/l to 2.90 mmol/l after lα‐hydroxyvitamin D3 therapy in Group I, while in Group II it rose from 2.66 mmol/l to 2.69 mmol/l after phosphate reduction and then to 2.87 mmol/l on lα‐hydroxyvitamin D3. The plasma calcium in Group I and II was not significantly different after 8 months therapy. The plasma phosphate in Group II showed no significant change during the 8 months.There was considerable increase in corneal calcification, pruritus and soft tissue calcification in Group I on lα‐hydroxyvitamin D3 whde in Group II there was little increase. The difference in these parameters of metastatic calcification was attributed to the higher plasma phosphate in Group I.Resolution of sub‐periosteal erosions occurred in seven of eleven patients in Group I and only four of nine in Group II. Periosteal new bone formation developed in six patients in Group I and none in Group II.