Should dialysate calcium concentration be standardised or individualised?
The 2003 K/DOQI bone metabolism guidelines recommend a standard dialysate calcium concentration of 1.25 mmol/l. Studies of calcium balance that take ultrafiltration, as well as changes in ionised calcium, into account show that patients lose calcium when treated with this dialysate Ca. Compensation for negative calcium balance will usually be required in patients with normal or high bone turnover, but may be impossible if the recommendations to restrict intake of calcium, and hold vitamin D therapy if serum phosphate is high, are followed. A literature review suggests that conversion to 1.25 mmol/l dialysate Ca is beneficial in selected, but not all, patients. Conversion to higher dialysate Ca levels has been shown to improve control of calcium, phosphate and PTH, again in selected patients. Given the important role that dialysate calcium concentration plays in the management of renal bone disease, it should be prescribed on an individual basis like other medications.