Factors influencing the removal of protein-bound uremic toxins in hemodiafiltration.

INTRODUCTION

Protein-bound uremic toxins (PBUTs) have a high affinity for albumin and they are associated with increased cardiovascular morbidity and mortality in hemodialysis patients. Among them, p-cresyl sulfate (pCS) and indoxyl sulfate (IS) stand out due to their high toxicity. Postdilution hemodiafiltration (HDF) is one of the dialysis techniques that has shown the greatest benefits in terms of patient survival.

MATERIALS AND

METHODS

This observational, single-center, cross-sectional study evaluated PBUT clearance in 137 patients undergoing post-dilution HDF, analyzing the factors that influence their removal. Reduction ratios (RRs) of IS and pCS were measured, as well as their correlation with dialysis parameters and clinical variables.

RESULTS

The mean RR for IS was 53.4% ± 9.3%, and for pCS, 48.2% ± 11.3%. A significant correlation was observed between the RR of both toxins (r = 0.606; P < .01), suggesting similar elimination mechanisms. In addition, total convective volume showed a positive correlation with the RR of pCS (r = 0.19; P = .027) and a weak correlation with the RR of IS (r = 0.155; P = .07). A significant difference in clearance was found according to sex, with higher RRs in women (P < .001 for IS and P = .008 for pCS).

CONCLUSIONS

The clearance of PBUTs is primarily diffusive. Enhancing all variables related to this physical principle will improve the elimination of these toxins. Postdilution HDF with high convective volume slightly increases this clearance. However, the results remain insufficient given the high toxicity of these molecules. New strategies, such as the use of adsorptive membranes and competitive molecules, are needed to optimize their removal and reduce the negative cardiovascular impact in hemodialysis patients.