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Fractional Excretion of Urea (FE_urea) Calculator

FE_urea = (U_urea · S_creat) / (S_urea · U_creat) × 100.

Compute the fractional excretion of urea — useful in patients on diuretics, where FE_Na can be misleading: FE_urea = (urine urea × serum creatinine) / (serum urea × urine creatinine) × 100. < 35 % suggests pre-renal AKI; > 50 % intrinsic.

Priya Venkatesan By Priya Venkatesan
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

FE_urea = (U_urea · S_creat) / (S_urea · U_creat) × 100

In depth

Compute the fractional excretion of urea — useful in patients on diuretics, where FE_Na can be misleading: FE_urea = (urine urea × serum creatinine) / (serum urea × urine creatinine) × 100. < 35 % suggests pre-renal AKI; > 50 % intrinsic.