Automated Setting of Individualized Sodium Technology

Inclusion Criteria: * Subject must be in clinically stable condition as judged by the treating physician, and demonstrated by stable medical history, physical examination, and laboratory testing for 30 days prior to enrollment. * Subject must be receiving HD or hemodiafiltration (HDF) for at least 30 days prior to study enrollment, be dialyzing a minimum of 3 times per week in an in-center setting and each treatment session must be between 3.5 and 5 hours in duration. * Subject has a stable functioning vascular access (arteriovenous \[AV\] fistula, graft, or dual-lumen tunneled catheter) based on the judgment of the treating physician and is performing dual-needle therapy with an actual blood flow rate of 250 - 400 mL/min. * Subject has a pre-dialysis plasma sodium of ≥132 mmol/L for at least 60 days prior to study enrollment. * Subject has achieved a dialysis dose of stdKt/Vurea ≥ 2.1 within 60 days prior to enrollment. * Subject has a pre-dialysis hemoglobin ≥ 90 g/L measured at Screening. Exclusion Criteria: * Female subjects who are pregnant, lactating, or planning to become pregnant during the study period. * Subjects who have a significant psychiatric disorder or mental disability that could interfere with the subject's ability to provide Informed Consent and/or comply with protocol procedures. * Subjects with a medical condition that the investigator thinks may interfere with the study objectives. * Subjects with significant signs of access recirculation as judged by the treating physician.