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

Abstract Rational & 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. Maintenance hemodialysis patients were screened for coronary artery calcification (CAC) and bone mineral density (BMD), and those with CAC score≥300 were included and matched according to the initial CAC score. Intervention and the control groups consisted of 20 patients in each arm. Interventions High (1.75 mEq/L) or standard dialysate magnesium (0.7 mEq/L) concentration delivered for 26 weeks. Outcomes Changes in CAC score and BMD and the progression of CAC. Safety outcomes included occurrence of cramps recorded as per usual care. Results The median CAC score of all patients was 1792. Serum and ionized magnesium increased substantially in the high dialysate magnesium group. At the end of the study, CAC score increased significantly in both groups, with no significant difference between groups. The number of participants with CAC progression was comparable among the two groups. In exploratory subgroup analyses stratified by the median CAC score, a significant decline in CAC and fewer participants with CAC progression were observed among the subgroup with lower CAC score that received high dialysate magnesium. BMD was largely unchanged in either group. The number of participants experiencing cramps and the number of episodes of muscle cramps were markedly lower among patients who received high dialysate magnesium. Limitations Participants had severe vascular calcification at baseline, therefore findings might not apply to those with less established calcification. Cramps were not systematically ascertained. Conclusions High dialysate magnesium did not ameliorate the progression of CAC or improve the BMD among hemodialysis patients with severe calcification, although muscle cramps appeared less frequent among those treated with high dialysate magnesium. A possible favorable impact of high dialysate magnesium in individuals with mild to moderate calcification requires further study.