FEUrea Calculator (Fractional Excretion of Urea)
Calculate fractional excretion of urea with BUN, urea, and creatinine conversion.
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FEUrea
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Converted urine BUN
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Converted serum BUN
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See the related FENa calculator for the sodium-based fractional-excretion equation.
About
Fractional excretion of urea (FEUrea) compares urine and serum urea with paired creatinine values. BUN reports only urea nitrogen and is not numerically interchangeable with total urea, so each input is normalized before calculation. FEUrea is an adjunctive laboratory estimate and is not guaranteed to outperform FENa during diuretic exposure.
Formula
Interpretation
Units: Urine and serum urea/BUN are converted to the same BUN basis; both creatinine values are converted to mg/dL.
Worked example: Urine BUN 300 mg/dL, serum BUN 60 mg/dL, urine creatinine 100 mg/dL, and serum creatinine 2 mg/dL gives FEUrea 10%.
Limitations: Sepsis, CKD, catabolism, urea handling, timing, and other factors can affect the result. No single threshold establishes an AKI cause.
FAQ
Disclaimer
Educational and informational reference only. Not intended to replace professional medical advice, diagnosis, treatment, or independent verification.