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🩸 Fractional Excretion of Sodium (FENa)

Differentiate between prerenal azotemia and acute tubular necrosis (ATN) in acute kidney injury cases using the FENa formula.

What is this tool?

When a patient presents with an abrupt decline in kidney function, identifying the root cause is crucial. This tool calculates the fraction of sodium filtered by the kidney that ends up excreted in the urine, allowing you to quickly distinguish between dehydration (prerenal) and kidney tissue damage (intrinsic).

How it works?

Input four basic lab variables: Serum Sodium, Urinary Sodium, Serum Creatinine, and Urinary Creatinine. The calculator determines the FENa percentage: a score <1% points to a prerenal state, while a score >2% suggests intrinsic kidney injury.

Is it free for all?

Yes, Free for everyone! Ideal for nephrology sub-specialists, intensivists, and hospitalists working through diagnostic differentials.

Clinical Reference Source: Espinel CH. The FENa test. Use in the differential diagnosis of acute renal failure. JAMA. 1976.

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