Nephrology
Fractional Excretion of Urea (FEUrea)
AKI differentiation when diuretics on board.
Fractional Excretion of Urea (FEUrea) calculator
Result
13.3%
< 35% — Pre-renal
How to use it
- 1
Use when diuretics given. Furosemide increases urinary Na excretion → FENa falsely elevated. FEUrea not affected.
- 2
Spot urine and serum samples. Urine urea, BUN, and both creatinines simultaneously.
- 3
Threshold < 35% = pre-renal. Less studied than FENa; use together with clinical picture.
When to use it
- AKI on diuretics
- ICU / heart failure patients on furosemide — FEUrea more reliable.
- Oliguric AKI
- If FENa inconclusive and diuretics given, FEUrea may clarify.
- Cirrhosis
- Hepatorenal syndrome: FEUrea may remain < 35% despite renal parenchymal injury.
A reference for clinicians and students, not medical advice. A score supports a decision; it does not make one. Check every result against the patient in front of you and your local protocol.
At a glance
- Specialty
- Nephrology
- Inputs
- 4
- Type
- Formula
