How to Use FEUrea Calculator
- Enter the blood urea nitrogen value in the BUN field. Keep it in the same laboratory unit family used with the urine urea value.
- Enter serum creatinine and urine creatinine. The creatinine units should match each other because they form the second ratio in the formula.
- Enter urine urea, then review the FEUrea percentage and the threshold note. This tool highlights the supplied threshold bands of below 35%, 35% to 50%, and above 50%.
Formula & Theory - FEUrea Calculator
FEUrea Calculator uses this core formula:
FEUrea = (Urine urea × Serum creatinine) / (Urine creatinine × BUN) × 100%FEUrea compares how much urea appears in urine relative to serum urea while correcting for creatinine concentration. The creatinine terms help adjust for urine concentration, so the result is a fractional excretion percentage rather than a raw urine concentration. In acute kidney injury review, clinicians may use FEUrea when diuretic therapy makes sodium-based indices less reliable. The interpretation is still contextual: volume status, timing of samples, catabolism, liver disease, and medications can all change the meaning of the percentage.
Use Cases for FEUrea Calculator
- Reviewing AKI workups when BUN, creatinine, and urine chemistry are already available.
- Checking whether a FEUrea value falls into the user-specified prerenal, renal, or indeterminate threshold band.
- Teaching residents or students how urea and creatinine ratios combine into a fractional excretion result.