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Fractional Excretion of Urea (FeUrea) Calculator

Distinguish pre-renal from intrinsic renal failure.

Calculates FeUrea = (urine urea × serum creatinine) / (serum urea × urine creatinine) × 100%. FeUrea < 35% suggests pre-renal cause (useful in patients on diuretics).

Marcus Laurent By Marcus Laurent
Published Last reviewed 1 min read

Inputs

mg/dL
mg/dL
mg/dL
mg/dL

Results

Enter values and click Calculate to see results.
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How to use this calculator

  1. Fill in the inputs above using the units you already have.
  2. Values update automatically as you type — no submit button needed.
  3. Hover any result row for the underlying formula and intermediate values.

Formula

FeUrea = (U_urea · S_cr) / (S_urea · U_cr) × 100

In depth

Calculates FeUrea = (urine urea × serum creatinine) / (serum urea × urine creatinine) × 100%. FeUrea < 35% suggests pre-renal cause (useful in patients on diuretics).