Serum Magnesium and Risk of Arteriovenous Fistula Thrombosis in Hemodialysis: A Retrospective Cohort Study

Background Arteriovenous fistula (AVF) thrombosis is a major cause of vascular access failure in patients undergoing maintenance hemodialysis (HD). Although magnesium has established vascular protective properties, its relationship with AVF thrombosis remains poorly characterized. This study aimed to examine the association between serum magnesium levels and the risk of AVF thrombosis in a retrospective cohort of HD patients. Methods This bi-center retrospective cohort study included 408 HD patients treated between January 2020 and May 2025. Baseline serum magnesium was categorized into tertiles: T1 (< 0.87 mmol/L), T2 (0.87–0.97 mmol/L), and T3 (≥ 0.98 mmol/L). The primary outcome was the first clinically confirmed episode of AVF thrombosis. Kaplan–Meier estimates and Cox proportional hazards models adjusted for demographic, clinical, and dialysis-related variables were used to assess the association. Sensitivity and subgroup analyses were performed to evaluate the robustness of findings. Results Over a median follow-up of 33.5 months, 83 patients (20.3%) experienced AVF thrombosis. Compared to T1, patients in T2 and T3 groups had significantly lower thrombotic risk: HR 0.57 (95% CI: 0.40–0.82, p = 0.002) and HR 0.46 (0.28–0.77, p = 0.003), corresponding to a 1.75- and 2.17-fold higher risk for T1 versus T2 and T3, respectively. Independent predictors of increased AVF thrombosis risk included older age (HR 1.05 per year, 95% CI: 1.02–1.09), higher serum phosphate (HR 1.11 per 0.1 mmol/L, 95% CI: 1.03–1.48), and calcium-based phosphate binder use (HR 1.02, 95% CI: 1.003–1.27). Protective factors included higher dialysis adequacy (spKt/V; HR 0.16, 95% CI: 0.11–0.35) and statin therapy (HR 0.35, 95% CI: 0.14–0.86). The association between low magnesium and AVF thrombosis remained robust in sensitivity and subgroup analyses. Conclusions Low serum magnesium (< 0.87 mmol/L) is independently associated with a twofold increased risk of AVF thrombosis in HD patients. Magnesium may represent a modifiable target for improving vascular access outcomes, warranting further prospective investigation.