MAGnesium in Chronic HemoDialysis

Background: In observational hemodialysis cohort studies, lower serum magnesium levels are associated with overall and cardiovascular mortality. In vitro, magnesium inhibits calcification of vascular smooth muscle cells. Based on these data, we hypothesize that lower magnesium is a new risk factor for cardiovascular disease in CKD. The dialysate might be an attractive way to increase plasma dialysate concentration.

Objective/Research questions: Determine feasibility to increase plasma dialysate magnesium concentration by means of increasing dialysate magnesium concentration.

Methods: A prospective randomized double blind standard of care controlled trial in patients on a regular 3 times weekly hemodialysis schedule. The control group continues dialysis with the standard dialysate magnesium concentration of 0.50 mmol/L. In the intervention group, the dialysate magnesium concentration is step-wise increased from 0.50 mmol/L to 0.75 mmol/L to 1.00 mmol/L, followed by a gradual decrease to the standard dialysate magnesium concentration of 0.50 mmol/L.

Primary outcome:

1. The difference between plasma magnesium concentration after the long interdialytic interval in the intervention group with incremental dialysate magnesium concentration and plasma magnesium concentration in the control group with standard dialysate magnesium concentration at the end of week 8.

2. The difference in change of plasma magnesium concentration after the long interdialytic interval from baseline to the end of week 8 between the intervention group and the control group.

Country of recruitment: The Netherlands

Increasing plasma magnesium concentration in hemodialysis patients by means of increasing dialysate magnesium concentration is feasible.

- week 0-11 plasma magnesium measurements

- week 0, 4, 8 study visit

Stepwise increase of magnesium concentration in the dialysate:

- Week 0: continuation of standard 0.50 mmol/L dialysate magnesium

- Week 1, 2, 3, 4: dialysate magnesium 0.75 mmol/L

- Week 5, 6, 7, 8: dialysate magnesium 1.00 mmol/L if pre-dialysis plasma Mg <1.15 mmol/L in week 4; dialysate magnesium 0.75 mmol/L if pre-dialysis plasma Mg 1.15 or above in week 4

- Week 9: dialysate magnesium concentration reduction of 0.25 mmol/L (to either 0.75 mmol/L or 0.50 mmol/L)

- Week 10, 11: dialysate magnesium 0.50 mmol/L