Hypomagnesemia and cause-specific mortality in hemodialysis patients: 5-year follow-up analysis

Introduction: The aim of this prospective study was to evaluate the association between serum magnesium (Mg) and mortality, in particular the cause-specific mortality of Mg and other risk factors in hemodialysis (HD) patients. Methods: We studied a cohort of 185 HD patients receiving thrice-weekly HD treatment, on a dialysate Mg concentration of 0.5 mmol/L. We stratified 3 patient groups according to the level of Mg: lower (<1.1 mmol/L), intermediate-reference (1.1 to <1.3 mmol/L), and higher (Mg >1.3 mm/L). Results: During the 5-year follow-up, 60 patients died, with cardiovascular (CV) disease as the predominant cause (73.3%). Hazard ratio (HR) for all-cause and CV mortality were 2.55 and 2.67 in the lower versus intermediate Mg group, but there was no significant association between the higher and intermediate Mg group. Univariate Cox regression analysis showed that Mg <1.1 versus 1.1-1.30 mml/L with HR 2.34, was a significant univariate predictor for increased mortality in addition to the Hb <110 g/L, Alb <40 g/L, C-reactive protein (CRP) >= 10 mg/L and brain natriuretic peptide >1,200 pg/mL. However, in the multivariate analysis only CRP >= 10 mg/L with HR 3.89 was a significant predictor of mortality. Subgroup analyses showed that among patients with CRP >10 mg/L, HR for all-cause and CV mortality of the lower versus intermediate Mg group were 1.96 and 2.39, respectively, not reaching significance for the higher versus intermediate Mg group. Conversely, there was no association between Mg level and all-cause and CV mortality within these 3 groups among patients with CRP <10 mg/L. Conclusions: Lower serum Mg level was significantly associated with an increased all-cause and cardiovascular mortality in HD patients, especially in inflamed patients.