FENa Calculator
Calculate Fractional Excretion of Sodium for kidney function assessment
FENa Formula
FENa = (Urine Sodium × Serum Creatinine) / (Serum Sodium × Urine Creatinine) × 100
FENa = (UNa × SCr) / (SNa × UCr) × 100
Result is expressed as a percentage (%)
Clinical Interpretation
FENa < 1%: Suggests prerenal azotemia (decreased renal perfusion)
FENa > 2%: Suggests intrinsic renal failure (acute tubular necrosis)
FENa 1-2%: Borderline/indeterminate - consider clinical context
Note: FENa is the gold standard for differentiating prerenal from intrinsic renal failure