Fractional Excretion of Urea (FEUrea)
Differentiates between prerenal azotemia and acute tubular necrosis in patients with acute kidney injury. Similar to the FENa, but can be used on patients on diuretics.
Advice
This tool is considered an adjunct in the evaluation and management of AKI; consider the full clinical picture, and do not use any single test as the sole basis for clinical decision-making.
Management
FEUrea <35%:
- Diagnosis is more likely to be prerenal azotemia.
- Consider increasing effective circulating volume based on the clinical situation (e.g., IV fluid administration).
FEUrea >50%:
- Diagnosis is more likely to be intrinsic renal disease (e.g., ATN).
- Treat the underlying cause of ATN.
- Consider withdrawing nephrotoxic medications.
Critical Actions
Rule out urinary tract obstruction when clinically appropriate before applying this tool.