Acetate is the primary acidifying solution used in bicarbonate-based hemodialysis worldwide. It has been published in small trials or case series that the addition of acetate is associated with a rise in nitric oxide production of vascular smooth muscle cells, endothelial cells and myocardial cells as a sign of vascular dysfunction. Furthermore clinical side effects of dialysis e.g. nausea, malnutrition, intradialytic blood pressure drops, induction of proinflammatory cytokines and activation of complement and leukocytes have been described with acetate.

Citrate on the other hand was associated with: Acid-base disorders (metabolic alkalosis), Disturbances of the calcium homeostasis (Hypocalcemia), but also anti-inflammatory effects. Both dialysate additives (citrate and acetate) are commercially available and are used world wide in dialysis centers.

The investigators hypothesize that substitution of acetate by citrate reduces the cardiovascular risk (measured by a change in the surrogate parameter of pulse wave velocity and Augmentation index) and might improves quality of life in the participants. Furthermore the investigators speculate that citrate in the dialysis solution could reduce systemic inflammation in the participants of the study.

Inclusion Criteria:

• time since initiation of dialysis > 3 months
• age > 18 years
• dialysis 3x/week for > 4 hrs

Exclusion Criteria:

• ongoing infection
• pregnancy
• lack of written and informed consent