Calculator

Fractional excretion of sodium

New

(Urine Na × Plasma Cr) ÷ (Plasma Na × Urine Cr) × 100.

mmol/L
mg/dL
mmol/L
mg/dL

FeNa

0.29 %

< 1%: pre-renal pattern (unreliable on diuretics)

< 1%: pre-renal pattern (unreliable on diuretics)
1-2%: indeterminate
> 2%: intrinsic renal (ATN) pattern

Formula

(una * pcr) / (pna * ucr) * 100

References

  1. Espinel CH. The FENa test: use in the differential diagnosis of acute renal failure. JAMA 1976;236:579-81.

Used in

AKI work-up

Calculators support, not replace, clinical judgement. Check inputs and units, and confirm doses with your unit protocol.