Dialysate Magnesium and Coronary Artery Calcification, Bone Mineral Density, and Cramping in Maintenance Hemodialysis: A Quasi-experimental Study

RATIONALE & OBJECTIVE: Recent evidence suggests a role for magnesium as a calcification inhibitor. Increased magnesium abundance may attenuate vascular calcification and promote bone formation. STUDY DESIGN: Parallel-group, 1:1-allocation-ratio, quasi-experimental study. SETTING & PARTICIPANTS: The study was conducted at hemodialysis centers in Bangkok, Thailand. Patients receiving maintenance hemodialysis were screened for coronary artery calcification (CAC) and bone mineral density (BMD), and those with a CAC score of ≥300 were included and matched according to the initial CAC score. The intervention and control groups consisted of 20 patients in each arm. INTERVENTIONS: A high (1.75 mEq/L) or standard (0.7 mEq/L) dialysate magnesium concentration was delivered for 26 weeks. OUTCOMES: Changes in the CAC score and BMD and the progression of CAC. The safety outcomes included occurrence of cramps recorded as per usual care. RESULTS: The median CAC score of all patients was 1,792. Serum and ionized magnesium concentrations increased substantially in the high dialysate magnesium group. At the end of the study, the CAC score increased significantly in both the groups, with no significant difference between the groups. The number of participants with CAC progression was comparable between the 2 groups. In exploratory subgroup analyses stratified by the median CAC score, a significant decline in CAC and fewer participants with CAC progression were observed in the subgroup with lower CAC scores that received the high dialysis magnesium concentration. Bone mineral density was largely unchanged in both groups. The number of participants experiencing cramps and the number of episodes of muscle cramps were markedly lower among patients who received the high dialysis magnesium concentration. LIMITATIONS: The participants had severe vascular calcification at baseline; therefore, the findings might not apply to those with less-established calcification. Moreover, cramps were not systematically ascertained. CONCLUSIONS: The high dialysis magnesium concentration did not alleviate the progression of CAC or improve BMD in patients with severe calcification receiving hemodialysis; however, muscle cramps were less frequent among those treated with high dialysate magnesium. Further study is required to determine a possible favorable effect of high dialysis magnesium concentration in individuals with mild-to-moderate calcification.