Protein-Bound Uremic Toxins Removal with Medium Cut-Off Membranes: A Pilot Study Showing No Superiority over High-Flux Dialysis

Abstract

Introduction: Protein-bound uremic toxins such as advanced glycation end products (AGEs) are poorly cleared by conventional dialysis. Medium cut-off (MCO) membranes have been proposed to enhance their removal, but clinical evidence remains limited.

Methods: In this prospective pilot study, 8 maintenance hemodialysis patients were assigned to receive a single dialysis session using either an MCO or high-flux (HF) membrane. Serum levels of N-carboxymethyllysine (CML), soluble receptor for AGEs (sRAGE), and prolactin were measured pre- and post-dialysis. Reduction ratios corrected for hemoconcentration (RRc) were compared between groups.

Results: The median RRc for CML was similar between MCO (36.9%) and HF (35.6%) membranes (p = 0.686). sRAGE reduction was lower with MCO membranes (21.8% vs. 41.9%, p = 0.114), while prolactin clearance was slightly higher (58.1% vs. 50.9%, p = 0.486). No statistically significant differences were observed.

Conclusion: MCO membranes did not demonstrate superior removal of protein-bound toxins compared to HF membranes in this pilot study. These findings highlight the need for alternative strategies, such as adsorption, and larger studies to define the clinical utility of MCO technology.

Keywords: Advanced glycation end products; Hemodialysis; Medium cut-off membranes; N-carboxymethyllysine; Protein-bound uremic toxins.