Fractional Excretion of Sodium (FENa) Calculator
Estimate how the kidneys handle sodium from urine and serum values.
Your result
Values below about 1% suggest the kidneys are conserving sodium (often prerenal). Values above 2% are more typical of intrinsic kidney injury. Diuretic use changes the result.
Medical disclaimer: This tool is for education and is not medical advice. Read more.
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Frequently asked questions
What does the Fractional Excretion of Sodium (FENa) Calculator do?
Estimate how the kidneys handle sodium from urine and serum values. Enter your values and the result and chart update instantly.
How accurate is it?
It uses published, widely used formulas. Results are estimates for education and planning, not a diagnosis. Talk to a qualified clinician about decisions affecting your health.
Is my information stored or shared?
No. All calculations run in your browser and nothing you type is sent to a server or saved.
What can I search to find this tool?
People find it by searching for: fena calculation; fractional excretion sodium; kidney failure cause sodium.