FENa (Fractional Excretion of Sodium)
Distinguishes pre-renal azotemia from acute tubular necrosis.
RESULT
FENa (Fractional Excretion of Sodium)
What is FENa (Fractional Excretion of Sodium)?
Distinguishes pre-renal azotemia from acute tubular necrosis. FENa is intended for use in: Adults.
How to Use the FENa Calculator
- Enter Urine sodium in mEq/L.
- Enter Plasma sodium in mEq/L.
- Enter Urine creatinine in mg/dL.
- Enter Plasma creatinine in mg/dL.
- Click Calculate to see your result and interpretation.
Formula & Version
This calculator uses formula version 1.0, last reviewed September 2026.
Clinical Considerations & Limitations
- Unreliable if the patient has recently received diuretics — consider FEUrea instead in that setting.
References
- Espinel CH, JAMA 1976;236:579-581
Frequently Asked Questions
What is FENa (Fractional Excretion of Sodium)?
Distinguishes pre-renal azotemia from acute tubular necrosis.
Who is FENa intended for?
Adults. Always confirm applicability to your specific patient before use.
What are the limitations of FENa?
Unreliable if the patient has recently received diuretics — consider FEUrea instead in that setting.
What formula or reference does FENa use?
Espinel CH, JAMA 1976;236:579-581
Is FENa a diagnosis?
No. FENa produces a score or estimate to support clinical decision-making — it is not a diagnosis and should be interpreted alongside full clinical judgement.
Medical Disclaimer: Medical calculators are provided for informational and educational purposes only. Results should not be used as a substitute for professional medical advice, diagnosis, or treatment. Always verify results with a qualified healthcare professional.
