Relationship between serum magnesium and nutritional index and mortality of peritoneal dialysis patients

Abstract

Objective The purpose of the study was to evaluate the association between serum magnesium and mortality and cardiovascular mortality in peritoneal dialysis patients and search for risk factors influencing serum magnesium. Methods This was a single center retrospective study, this study included peritoneal dialysis patients from January 1st, 2010 to June 30th, 2017 and followed to December 31th, 2017 in our hospital. Demographic, clinical and laboratory indicators of the patients were collected. Risk factors influencing serum magnesium and evaluated the association between serum magnesium and mortality and cardiovascular mortality in peritoneal dialysis patients were searched for. The primary end point was all cause mortality and cardiovascular mortality of peritoneal dialysis patients. Hypermagnesemia was defined as serum magnesium greater than 1.02 mmol/L. Results 204 peritoneal dialysis patients were included in our study, 53.4% of them were male, 46.6% were female and 27.4% of them were diagnosed with diabetic nephropathy. The average age of patients starting peritoneal dialysis was (49.4±15.3) years old and the median duration of peritoneal dialysis was 32 months. Among them, 65 patients (31.8%) had hypermagnesemia, 135 patients (66.2%) had normal serum magnesium, only 4 patients (2%) had hypomagnesemia. Serum magnesium levels had a negative association with age (r=-0.158, P=0.024), and had a positive association with serum albumin (r=0.258, P<0.001), serum phosphorus (r=0.251, P<0.001), serum creatinine (r= 0.223, P=0.001). According to Logistics regression analysis, serum albumin level (P=0.018) was the independent influencing factor affecting serum magnesium level in patients with peritoneal dialysis. There was no significant difference in all cause mortality (P=0.251) and cardiovascular mortality (P=0.693) between serum magnesium normal group and hypermagnesemia group. In the multivariate Cox regression analysis, hyperphosphatemia (HR=0.350, P=0.021), high parathyroid hormone level (HR=2.822, P=0.001), the history of diabetes (HR=7.651, P<0.001) were predictors of all cause mortality in peritoneal dialysis patients. The history of diabetes (HR=16.595, P<0.001) was a major predictor of cardiovascular mortality in peritoneal dialysis patients. Conclusion (1)Serum albumin level was the independent influencing factor affecting serum magnesium level in patients with peritoneal dialysis. (2)Serum magnesium had no effect on mortality of peritoneal dialysis patients. (3)Hyperphosphatemia, high parathyroid hormone level, the history of diabetes had association with all cause mortality and the history of diabetes had association with cardiovascular mortality in peritoneal dialysis patients independently. Key words: Serum magnesium level; Hypermagnesemia; Peritoneal dialysis; Influencing factor; Mortality