Beyond Diffusion: Clinical Perspectives on Online Hemodiafiltration and Medium Cut-Off Dialyzers

Online hemodiafiltration (OL-HDF) and medium cut-off (MCO) dialyzers augment diffusionbased hemodialysis (HD) with convective clearance to enhance removal of middle molecules.In large-scale randomized trials, OL-HDF appears to reduce all-cause, cardiovascular, and infection related mortality compared to high-flux HD, particularly when convection volumes exceed 23 L per session.Data suggests a graded effect; higher achieved convection volumes are associated with greater benefit, and advantages are observed across analysed subgroups.Evidence also indicates better preservation of patient-reported quality of life compared to high-flux HD.Largescale observational registry data, while subject to inherent limitations, support beneficial outcomes and generalizability to routine clinical practice.MCO membranes enhance middlemolecule clearance on conventional hemodialysis machines via enlarged pore size and internalfiltration-back filtration.However, long-term clinical data remain limited, and the convective component is not externally measured or prescribed.This perspective distils mechanistic and clinical insights on both OL-HDF and MCO HD and evaluates published evidence, including solute clearance studies, mortality outcomes and patient-reported quality-of-life data.We outline actionable prescription strategies and opportunities for individualized treatment optimization.Our goal is to provide clinicians with a concise roadmap to personalize and integrate convectionenhancing therapies in everyday practice.