Clearance of Magnesium in Peritoneal Dialysis Patients: A Single-Center Study

Abstract

Objective: This retrospective study aimed to investigate the clearance of magnesium (Mg) in peritoneal dialysis (PD) patients and its influencing factors. Methods: The demographic information, clinical characteristics and laboratory data of the patients were collected. According to the corrected serum Mg (cS-Mg) concentration, patients were divided into 3 groups including hypomagnesemia (Mg²⁺ < 0.77 mmol/L, group A), normal serum Mg concentration (0.77 mmol/L ≤ Mg²⁺ ≤1.03 mmol/L, group B), and hypermagnesemia (Mg²⁺ > 1.03 mmo/L, group C). Results: One hundred and fifteen patients were enrolled, and their mean 24 h-peritoneal Mg clearance was 39.75 ± 17.42 mg. The mean normalized peritoneal Mg clearance rate was 1.82 ± 0.82 L/day/1.73 m². Twenty-four-hour peritoneal Mg clearance of group A was significantly lower than that of group C (p < 0.05). Bivariate correlation analysis showed that cS-Mg was positively correlated with peritoneal dialysate Mg concentration (p < 0.01). cS-Mg was negatively correlated with the normalized peritoneal Mg clearance rate (p < 0.05). The normalized peritoneal Mg clearance rate was positively correlated with prealbumin (p < 0.05), daily peritoneal protein loss (p < 0.01) and the normalized PD-creatinine clearance rate (p < 0.01). The normalized peritoneal Mg clearance rate was also negatively correlated with the normalized renal-creatinine clearance rate (p < 0.01). Furthermore, cS-Mg of patients with continuous ambulatory PD (CAPD) was significantly lower than that of patients with daytime ambulatory PD (DAPD, p < 0.01). The normalized peritoneal Mg clearance rate of patients with CAPD was significantly higher than that of patients with DAPD (p < 0.01). Moreover, among the patients with different peritoneal transport characteristics of peritoneal equilibration test, the normalized peritoneal Mg clearance rate of high average transport patients was significantly higher than that in those with low transport, low average transport and high transport (p < 0.05). Conclusions: Serum Mg could be partly cleared by PD. The peritoneal Mg clearance was positively related with serum Mg concentration, which was concentration-dependent. Peritoneal Mg clearance was negatively correlated with the residual renal function, while being positively correlated with the nutritional status and daily peritoneal protein loss. Peritoneal Mg clearance was higher in patients with high transport characteristics or CAPD.