Effects of on-line hemodiafiltration regimens and dialysate composition on serum concentrations of magnesium and calcium ions

Background: Low-ionized magnesium and high-ionized calcium levels are associated with increased cardiovascular mortality in patients undergoing dialysis. We examined the effects of the dilution method, substitution volume, and dialysate of on-line hemodiafiltration on the total and ionized magnesium and calcium levels. Methods: Eighteen patients were randomly assigned to three dialysate groups: two acetic acid dialysate groups and one citrate dialysate group. Five treatment conditions were applied: pre-diluted on-line hemodiafiltration, postdiluted on-line hemodiafiltration, and hemodialysis. Results: The total and ionized serum levels of magnesium and calcium were evaluated and found to be unaffected by the dilution methods and substitution volumes. The albumin leakage was approximately 3 g/session under the pre-dilution and hemodiafiltration conditions, and approximately 4-5 g/session under the post-dilution condition. The ionized magnesium concentration decreased in the citrate dialysate group. Conclusion: The on-line hemodiafiltration parameters had a negligible effect on ionized magnesium and calcium; however, the use of citrate dialysate decreased the ionized magnesium levels, probably because of chelation.