Today it is well established that middle molecules comprise several compounds that are not effectively removed by high-flux dialyzers, and effective clearance of large middle molecules in the process of dialysis depends on the dialyzer membrane having large enough pore sizes, larger than the conventional high-flux dialyzers. Studies have found associations between levels of large middle molecule uremic toxins and immune dysfunction and inflammation, as well as adverse outcomes. This indicates that dialysis membranes having larger pores, enabling an expanded HD (HDx) with more effective removal of large middle molecules, can have a positive impact on the inflammatory state. While data is starting to appear on the long-term use of the HDx therapy, little is still known on how large middle molecules and inflammation markers are affected over time.

Inclusion Criteria:

• ESRD patients age between 18 - 80 years
• Clinically stable as judged by the treating physician for 30 days prior to enrollment, as demonstrated by pertinent patient medical history, physical examination, and laboratory testing
• Hemodialysis therapy with HDF for at least 3 months immediately prior to study enrollment

Exclusion Criteria:

• No informed consent provided
• Significant psychiatric disorder, mental disability, or other condition that may interfere with the patient's ability to provide informed consent
• Pregnant, breastfeeding, or planning to become pregnant
• Unstable vascular access associated with risk of low and variable extracorporeal blood flow rate (QB)
• Chronic liver disease, known paraprotein-associated disease, known bleeding disorders (e.g., gastrointestinal bleed, colonic polyps, small bowel angiodysplasia and active peptic ulcers)
• Major bleeding episode (i.e. soft tissue bleeding, blood in stool, joint damage, retinal bleeding, extensive mucosal bleeding, exsanguination, cerebral hemorrhage) ≤ 12 weeks prior to enrollment
• Blood (red blood cell) transfusion ≤ 12 weeks prior to enrollment
• Clinical signs of acute infection ≤ 4 weeks prior to enrollment
• Active cancer, except for basal cell or squamous cell skin cancer
• Positive serology test for human immunodeficiency virus or hepatitis infection
• Scheduled for planned interventions requiring hospitalization > 1 week
• Scheduled for living-donor transplantation within the study period
• Currently participating in another interventional clinical study or has participated in another interventional clinical study in the past 3 months that may interfere with this study