Expanded Dialysis (Hdx): Integrating Biophysical Innovation and Clinical Evidence Within the Evolving Paradigm of Extracorporeal Purification

Expanded dialysis (HDx) is an emerging extracorporeal purification modality enabled by medium cut‑off (MCO) membranes designed to enhance the removal of middle and large middle molecules. Positioned between high‑flux hemodialysis (HF‑HD) and online hemodiafiltration (HDF), HDx aims to broaden the spectrum of uremic toxin clearance while maintaining operational simplicity. This manuscript provides an integrated analysis of the biophysical rationale underlying MCO membranes, synthesizes current evidence on HDx performance, and evaluates its comparative role among contemporary renal replacement therapies. Although HDx demonstrates promising solute removal capabilities and practical advantages, long‑term outcome data remain limited, underscoring the need for further investigation.