Nephrology Free

Fractional Excretion of Sodium (FENa)

Differentiates prerenal from intrinsic renal failure.

Enter Values

Urine Sodium (mEq/L)

Range: 0 - 300

Serum Sodium (mEq/L)

Range: 100 - 180

Urine Creatinine (mg/dL)

Range: 0 - 500

Serum Creatinine (mg/dL)

Range: 0.1 - 30

Score

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About This Calculator

Author Carlos A. Espinel

First Published 1976

Evidence Standard clinical practice

Category Nephrology

Original Study The FeNa test: use in the differential diagnosis of acute renal failure (JAMA, 1976)

About The fractional excretion of sodium differentiates prerenal from intrinsic causes of acute kidney injury. FeNa <1% suggests prerenal; >2% suggests ATN.

Clinical Use Oliguric AKI without diuretic exposure. Invalid after diuretics, CKD, or contrast nephropathy.