Fractional Excretion Sodium calculation helps differentiate between pre-renal disease and acute tubular necrosis (ATN). Fractional Excretion of Sodium (FENa) Calculation: FENa = ( UNa * PCr ) / ( PNa * UCr ) * 100
|Urine Sodium (UNa)|
|Plasma Creatinine (PCr)|
|Plasma Sodium (PNa)|
|Urine Creatinine (UCr)|
- FENa < 1% usually suggestive to a prerenal state (e.g. volume depletion).
- FENa 1% to 2% may be seen as ATN or prerenal state.
- FENa > 2% usually suggestive to ATN