Low plasma magnesium concentration and future abdominal aortic calcifications in moderate chronic kidney disease

Abstract

Background: Higher plasma magnesium concentrations are associated with reduced cardiovascular disease risk in chronic kidney disease (CKD) patients. The importance of plasma magnesium concentration for vascular calcification in earlier stages of CKD remains underexplored. This study investigated whether plasma magnesium is a determinant for the presence and severity of vascular calcification in moderate CKD.

Methods: Retrospective analysis was performed using abdominal aortic calcification (AAC) scores in 280 patients with stage 3 and 4 CKD enrolled in the MASTERPLAN trial. Lateral abdominal X-ray was used to evaluate AAC. Plasma magnesium concentration were measured over time. A zero-inflated Poisson model determined the association between plasma magnesium concentration and AAC.

Results: 79 out of 280 patients did not have AAC, and in patients with AAC the median calcification score was 3.5 (interquartile range: 0.0-8.6). The mean plasma magnesium concentration was 0.76 ± 0.10 mmol/L at baseline. A 0.1 mmol/L higher plasma magnesium concentration was associated with lower AAC of 0.07 point (95% CI -0.28 - 0.14). A 0.1 mmol/L higher plasma magnesium lowered the odds of detecting any AAC by 30% (OR = 0.63; 95% CI 0.29-1.37). After 1 year and 4 years (at time of X-ray) of follow-up this association was attenuated (OR = 0.93; 95% CI 0.61-1.43 and 0.93; 95% CI 0.60-1.45, respectively). None of these associations reached statistical significance.

Conclusions: Plasma magnesium concentration at baseline is not associated with the risk for future AAC. Interventions increasing magnesium to avoid vascular calcification may have greatest potential in early CKD stages prior to onset of vascular calcification.

Keywords: Abdominal aortic calcification score; Chronic kidney disease; Magnesium; Vascular calcification.

Fig. 1

Plasma Mg²⁺ concentrations in non-dialysis CKD patients. Distribution of Mg²⁺ concentrations (A). Plasma Mg²⁺ concentrations for CKD patients with (indicated in white) and without (indicated in black) abdominal aortic calcifications (B). Dotted vertical lines indicate the reference values for Mg²⁺ concentration (0.7–1.1 mmol/L)

Fig. 2

Dose-response relation between Mg²⁺ and abdominal aortic calcification score. The abdominal aortic calcification (AAC)-score for each patient are presented individually and plotted against their plasma Mg²⁺ concentration at baseline. Dose-response relation between AAC and plasma Mg²⁺ concentration was investigated by creating a scatter plot and fitting a LOESS smoothed regression line. No transformations were considered due to linearity of the association. Dotted vertical lines indicate the reference values for Mg²⁺ concentration (0.7–1.1 mmol/L)