To investigate the serum magnesium level in its influencing factors and correlation with mortality of maintenance hemodialysis (MHD) patients.

On January 1, 2020 in Dalian Municipal Central Hospital, patients undergoing MHD and being eligible for entry were selected, whose general information, serum magnesium level, and other laboratory data were collected. A total of 757 patients were enrolled, including 452 males (59.7%) and 305 females (40.3%), with an average age of 59.77±13.82 years as well as a dialysis median time of 46 (18.5, 91.0) months. The average serum magnesium level was 1.09±0.15 mmol/L. The patients were divided into four groups according to the quartile of the serum magnesium level, including group 1 (serum magnesium <1.0 mmol/L, n=178), group 2 (1.0≤serum magnesium <1.08 mmol/L, n=203), group 3 (1.08≤ serum magnesium <1.17 mmol/L, n=171), and group 4 (serum magnesium ≥ 1.17 mmol/L, n=205). The follow-up was given until December 31, 2020, with the all-cause death as the end-point event. Kaplan-Meier software was used for survival analysis, and log-rank test method was used to compare the survival rate. Pearson or Spearman software was used for correlation analysis, while multiple linear stepwise regression method was applied to analyze the influencing factors of serum magnesium level. SPSS 24.0 method was used for statistical analysis, with P<0.05 as being of statistical significance.

There was no statistical difference in the age, dialysis age, and blood pressure among the four groups of patients, while there were statistical differences in blood hemoglobin, albumin, urea, creatinine, calcium, phosphorus, total cholesterol, ferritin, C-reactive protein (CRP), and Kt/V (P<0.05). Multiple regression analysis showed that blood hemoglobin, albumin, urea, calcium, phosphorus, and Kt/V were positively correlated with the serum magnesium level, while intact parathyroid hormone (iPTH), ferritin, and CRP were negatively correlated with the serum magnesium level (P<0.05). Log-rank test showed that the survival rates among the four groups were statistically different (χ²=13.113, P=0.004). The mortality of patients in the group with lower serum magnesium level was significantly higher than that of patients in the group with higher serum magnesium level. Multivariate Cox regression analysis showed that serum magnesium level was an independent risk factor for the mortality of MHD patients.

Attention should be paid to the serum magnesium level of MHD patients. The mortality of MHD patients was significantly higher in the group with lower serum magnesium level than in the group with higher serum magnesium level. Serum magnesium was an independent risk factor that could affect the mortality of MHD patients.