Fractional excretion of Sodium

Fractional Excretion of Sodium (FENa)
Plasma Na+ level	meq/L
Urine Na+ level	meq/L
Plasma Creatinine	mg/dl
Urine Creatinine	mg/dl

FENa=[(Urine Sodium)(Serum Creatinine)100]/[(Serum Sodium)*(Urine Creatinine)]
Fractional excretion of Sodium	%
FENa is calculated to evaluate acute renal failure or oliguria when urine output is <500ml/day
FENa<1%: Pre-renal disorder (anything that causes decreased effective renal perfusion)

FENa>1%: Intrinsic renal disorder (e.g. Acute tubular necrosis)

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