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Calculator: Fractional excretion of sodium (SI units)*

Calculator: Fractional excretion of sodium (SI units)*

Urine Na  
Serum Na  
Urine Cr  
Serum Cr  

Important: Inputs must be complete to perform calculation.

Decimal precision  


  • The fractional excretion of sodium (FENa) can be calculated by entering the values from simultaneously obtained urine and blood samples.
  • For this calculation, the urine creatinine concentration (Urine Cr) is entered as mcmol/L by default. Change the unit selector if you have a value in mmol/L.
  • * This calculator uses SI units (Système international d'unités) as the default for inputs. Do not use this calculator if you are using conventional units (also known as US units and gravimetric units); please refer instead to the conventional units version of this calculator.

Equations used
FENa = (Urine_Na / Serum_Na) / (Urine_Cr / Serum_Cr) * 100


  1. Stein JH. Internal Medicine, 4th ed, Mosby-Year Book, 1994.
Only digits 0 to 9 and a single decimal point (".") are acceptable as numeric inputs. Attempted input of other characters into a numeric field may lead to an incorrect result.

Information on this page may not appear correctly if printed.

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All information contained in and produced by the EBMcalc system is provided for educational purposes only. This information should not be used for the diagnosis or treatment of any health problem or disease. THIS INFORMATION IS NOT INTENDED TO REPLACE CLINICAL JUDGMENT OR GUIDE INDIVIDUAL PATIENT CARE IN ANY MANNER. Click here for full notice and disclaimer.

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