Comparison of Individualized Sodium Management Versus Standard Treatment in Hemodialysis

Inclusion Criteria: General: * Informed consent signed and dated by study patient and authorized physician * Minimum age of 18 years * The patient is legally competent and able to understand the nature, risks, meaning, and consequences of the clinical trial and can subsequently declare her/his consent for participation in the clinical trial * Patients with a chronic kidney disease stage 5D (end stage renal disease with a glomerular filtration rate of 15 ml/min or less) on dialysis as extracorporeal renal replacement therapy. Study-specific: * Patients on dialysis (HD/HDF), at least 4h treatment time thrice weekly ≥ 3 months using a standard dialysate with a prescribed sodium concentration of 136 mmol/L * Anuric patients (\<300mL/d; 1 measurement within last 4 weeks) * Patient fulfils one of the four following criteria: interdialytic weight gain over 4% of dry weight (mean value during run-in period) OR pre-dialytic systolic blood pressure over 180 mmHg (mean value during run-in period) OR intradialytic morbid events (hypotension, hypertension, cramps, headache) in at least three sessions during run-in period OR volume overload according to BCM (FO ≥2.5 L pre-dialysis or relative FO pre-dialysis ≥15% for men and ≥13% for women; one measurement during run-in period) \- Patients with a diffusive Na load of at least 1 mmoL/(L TBW) or 0.06g NaCl/(L TBW) (mean value during the run-in period). Exclusion Criteria: General: * Any conditions which could interfere with the patient's ability to comply with the study * Patient is not able to give informed consent according to European Medical Device Regulation and corresponding national regulations * In case of female patients: pregnancy (pregnancy test will be conducted at start and end of study with female patients aged ≤55 years) or lactation period * Participation in an interventional clinical study during the preceding 30 days * Previous participation in the same study Study-specific: * Patients treated with individualized sodium management over the last 3 months * Severe hypoalbuminemia (≤30 g/L; 1 measurement within last 4 weeks) * Hypernatremia (pre-dialytic plasma sodium concentration ≥145mmol/L; 1 measurement within last 4 weeks) * Uncontrolled diabetic patients with glycated hemoglobin (HbA1C) \>8%; 1 measurement within last 4 weeks * Impossible reliable measurement of the different compartments by bioimpedance due to lower limb amputation or wearing of a unipolar pacemaker or metallic prostheses * Life expectancy less than 6 months * ONLINEplus HF treatments/hemofiltration treatments * Single-needle treatments * Dry weight \< 40kg * Active or chronic infections (HIV, SARS-CoV-2, HBV, HCV)