Patients with renal impairment are usually advised to increase their fluid intake. There is currently, however, no evidence supporting this recommendation. In contrast,high fluid intake could be dangerous if urine excretion is reduced. In this study the researchers investigate whether increasing fluid intake from 2 to 4 litres per day has any influence on long-term renal outcome.

Inclusion Criteria:

• Patients with native kidney disease or chronic kidney transplant failure
• An effective glomerular filtration rate (eGFR) according the MDRD formula between 20 and 75ml/min/1.73m2
• Ejection fraction >20%
• Absence of liver cirrhosis or ascites
• No evidence of active glomerulonephritis or immunosuppressive therapy if native kidney disease
• Acute transplant rejection
• Urinary protein excretion below 3g/d
• Age between 18 and 70 years.

Exclusion Criteria:

• Therapy resistant edema
• Severe pulmonary disease
• Mean arterial pressure (MAP) > 120 mm Hg
• Pregnancy
• Kidney transplantation within three months prior to randomization