Factors Associated with β2-Microglobulin Removal in High-Volume Hemodiafiltration and Expanded Hemodialysis

Background: Beta-2-microglobulin (β2m), is linked to inflammation, immune dysfunction, and cardiovascular risk in hemodialysis. Advanced dialysis methods like hemodiafiltration (HDF) and expanded hemodialysis (HDx) enhance β2m clearance, but factors affecting its removal remain unclear. This study examined in vivo determinants in HDF and HDx patients. Methods: Patients with urine output <500 mL/day undergoing high-volume HDF (n=28) or HDx (n=20) were studied. Across 257 HDF and 179 HDx sessions, pre/post-dialysis β2m levels were measured. Logistic regression identified predictors of β2m reduction ratio (RRβ2m) >80%, and linear regression assessed factors influencing β2m removal efficiency. Results: Groups were similar except for age (HDF: 36 vs HDx: 45 years).In the HDF group, convective volume (CV) averaged 26.7 ± 3.8 L/session, blood flow (Qb) 365 ± 19.5 mL/min, dialysate flow (Qd) 447 ± 26 mL/min, session time (ST) 235 ± 17 min, and RRβ2m 84.8 ± 4.9%. In HDx group, Qb 363 ± 19 mL/min, Qd 539 ± 38 mL/min, ST 230 ± 21 min, ultrafiltration volume (UF) 2.1 ± 0.9 L, and RRβ2m 76.6 ± 5.5%. HDF showed higher RRβ2m (84.8% vs 76.6%) and greater likelihood of achieving RRβ2m >80% (OR 15.8, p<0.0001). In HDF, CV positively correlated with RRβ2m, and body weight (BW) was inversely associated. In HDx, BW negatively affected RRβ2m >80%, while ST and UF improved β2m removal. Qb, Qd, and vascular access had no significant effect in either group.[Figure 1] Conclusion: In HDF, CV is the key driver of β2m clearance; in HDx, ST and UF volume are primary factors. Higher BW reduces clearance efficiency in both. This findings support individualized care in anuric patients.Table1. Regression analysis for β2-m reduction target and reduction rate in HDF/HDx.