Role of magnesium in the risk of intradialytic hypotension among maintenance hemodialysis patients.

Introduction: Intradialytic hypotension (IDH) is a common complication in end-stage renal disease patients on hemodialysis (HD). It has been documented that several factors contribute to IDH. However, the relationship between serum electrolytes and the occurrence of IDH remains unclear. Our study aims to investigate the role of serum magnesium (Mg) for the risk of IDH in maintenance HD patients.

Methods: The retrospective study included adults starting HD before January 2009 in the blood purification center, Zhongshan Hospital, Fudan University, and treated thrice weekly with standard bicarbonate dialysate by low-flux HD. Patients' characteristics including age and sex, laboratory test results were collected. IDH was defined according to kidney disease outcomes quality initiative (K/DOQI) guidelines as a decrease in systolic blood pressure (SBP) by ≥20 mmHg or a decrease in mean arterial pressure (MAP) by ≥10 mmHg associated with clinical symptoms during HD. Multivariate logistic regression was employed to explore independent risk factors for IDH.

Findings: Among 423 patients recruited, 175 patients (41.4%) suffered from IDH. Compared with those with non-IDH, patients with IDH presented higher predialysis serum Mg levels. Univariate correlation analysis showed that predialysis serum Mg level was negatively correlated with SBP at 3 hours, 4 hours after dialysis (3 hours SBP r = -0.134 P = 0.006, 4 hours SBP r = -0.142 P = 0.003) and was positively correlated with the differences of blood pressure (BP) (SBP and MAP) (△SBP r = 0.195 P < 0.001, △MAP r = 0.155, P = 0.001). After adjustment for predialysis blood urea nitrogen, platelet distribution width, cardiac troponin T, fasting blood glucose, β2-microglobulin, and predialysis MAP, multivariate logistic regression analysis demonstrated that predialysis serum Mg level was one of the independent risk factors for IDH (odds ratio [95% confidence interval-CI]: 7.154 (1.568-32.637); P = 0.011). In addition, Mg levels of 1.15 mmol/L or higher were associated with a high incidence of IDH.

Discussion: Our findings suggested that higher predialysis serum Mg level was one of the independent risk factors for IDH among maintenance hemodialysis (MHD patients).