Serum β2-Microglobulin and Cardiac Valvular Calcification in Patients Receiving Maintenance Haemodialysis: Association, Calcification Burden and Diagnostic Performance

Background: Cardiac valvular calcification (CVC) is a prevalent cardiovascular complication among patients receiving maintenance haemodialysis (MHD). β2-Microglobulin (β2-MG), a middle-molecular-weight uraemic toxin, has been associated with cardiovascular disease in patients with chronic kidney disease. This study investigated the association between serum β2-MG and CVC and evaluated its discriminatory performance in patients undergoing MHD. Methods: This cross-sectional observational study enrolled 100 adult patients with end-stage kidney disease receiving MHD for at least 3 months. Serum β2-MG and mineral-bone parameters were measured, and transthoracic echocardiography was performed to assess CVC. Associations were evaluated using correlation and multivariable logistic regression analyses. Receiver operating characteristic (ROC) analysis was performed to assess the discriminatory performance of β2-MG. Results: CVC was detected in 52% of patients. Serum β2-MG levels were significantly higher in patients with CVC than in those without calcification (median, 148.05 vs. 28.80 mg/L; P < 0.001). β2-MG showed a strong positive correlation with calcification burden (r = 0.770, P < 0.001). Its association with CVC remained significant after adjustment for age, sex, dialysis duration, phosphorus, and parathyroid hormone (adjusted OR per 1 mg/L increase, 1.039; 95% CI, 1.022–1.057; P < 0.001). ROC analysis demonstrated an AUC of 0.941 (95% bootstrap CI, 0.888–0.983). A cut-off of 75.62 mg/L yielded 84.62% sensitivity and 97.92% specificity. Conclusion: Serum β2-MG was strongly associated with CVC and greater valvular calcification burden in patients receiving MHD. Its high discriminatory performance warrants validation in larger prospective multicentre studies.