FE Urea

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Use this calculator to calculate the fractional excretion of urea.

Units
SI
Imperial
Plasma urea (mg/dL or mmol/L)
Urine urea (mg/dL or mmol/L)
Plasma creatinine (mg/dL or µmol/L)
Urine creatinine (mg/dL or mmol/L)

About this calculator

Fractional Exceretion of Urea = Uur X Pcreat / Ucreat X Pur · 100%

Where
Uur = Urine urea
Pcreat = Plasma creatinine
Ucreat = Urine creatinine
Pur = Plasma urea

A fractional excretion of urea of < 35% is suggestive of pre-renal azotemia. Unlike when measuring the fractional excretion of sodium, FEUrea can be used even when patients are taking diuretics._

Citation

Carvounis CP, Nisar S, Guro-Razuman S. Significance of the fractional excretion of urea in the differential diagnosis of acute renal failure. Kidney Int 62(6):2223-2229. (2002)

Contributor

QxMD Nephrology contributing author: Daniel Schwartz, MD, FRCP(C)