Renal failure and high plasmatic level of urea have been associated with an increased risk of hemorrhage in surgical patients. There is only sparse data on the impact of renal replacement therapy on homeostatic parameters. The aim of this study is to describe potential changes in homeostatic parameters before and after renal replacement therapy.

Inclusion Criteria:

• critically ill patients
• acute renal failure
• renal replacement therapy
• plasmatic urea > 20

Exclusion Criteria:

• chronic renal failure
• platelet count less than 80 Giga
• V factor less than 70%

Critically ill patients with acute renal failure where the decision of renal replacement therapy has been made.