The relationship between serum magnesium and bio-electrical impedance variables in patients undergoing dialysis

Introduction: The relationships between serum magnesium(Mg) levels and body composition or clinical outcomes of incident dialysis patients remain unclear. The aim of this study was to evaluate the possible correlations between magnesium and bio-electrical impedance variables, a method of determining body composition in two groups of hemodialysis(HD) and peritoneal dialysis(PD) patients. Methods: This prospective observational study examined the relationships between Serum Mg levels and Bio-impedance variables including total body fat, body cell mass, extra cellular mass, total body water (TBW), intra and extra cellular water (ICW and ECW), ECW/ICW and phase angle (PA) in incident 38 HD and 34 PD patients since December of 2012 in Mashhad Imam Reza Hospital dialysis center. The correlation between Mg and bio-impedance variables was assessed applying the student test and Pearson’s correlation coefficient. Results: the average concentration of serum Mg was 1.22 mmol/L in HD patients and 1.20 mmol/L in PD patients which is well above the reference range in normal population. the average amount of body water and also ICW in patients were significantly higher than HD patients. Our statistical analysis showed no significant relation between serum Mg and Bio-electrical impedance variables in HD patients, however in PD patients, a statistically significant correlation was found between serum Mg and ECW (r = 0.48, p = 0.02), ICW (r =- 0.48, p = 0.02), and ECW/ICW (r = 0.43, p = 0.02). Conclusion: we speculated that there is a link between serum Mg level and intravascular and extravascular water content in PD patients, however we cannot prove any correlation between serum Mg level and Bio-impedance variables in such patients. This could be considered as a sign of Mg role in healthy cell function in PD patients.