While hypertension is one of the most common causes of end-stage renal disease, it is also present in the vast majority of hemodialysis patients. It is associated with higher cardiovascular morbidity and mortality in this group of patients. Altering dialysate sodium concentration presents a possibility of sodium balance control and blood pressure management. However, the ideal dialysate sodium concentration remains a topic for discussion.

Randomised and prospective single dialysis centre study is presented. The participants are randomly divided into 3 groups and will go through 3 periods of 2 months. A "low-to-high" dialysate sodium concentration group will start the study with 138 mmol/L in the first period, continue with 140 mmol/L in the second period and finish with 142 mmol/L. In the "high-to-low" group, the participants will go through the opposite design (reduction from 142 mmol/L to 138 mmol/L over 3 periods). One group will continue with 140 mmol/L throughout the study. Systolic and diastolic BP values before and after dialysis sessions, interdialytic weight gain, ultrafiltration, serum sodium concentration and the presence of hypotension between the groups in each period and within each group over all three periods will be evaluated.

Inclusion Criteria:

• At least 18 years of age
• Patients with end-stage renal disease hemodialysis for at least 3 months

Exclusion Criteria:

• Non-cooperation
• Active cancer
• Hospitalization during the course of the study