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Fractional Excretion of Sodium (FENa)

 

Input
 

Urine Na		mEq/L mmol/L
Serum Na		mEq/L mmol/L
Urine Cr		mcmol/L mg/dL mg/mL mmol/L
Serum Cr		mcmol/L mg/dL mmol/L

 
Result
 
Important: Inputs must be complete to perform calculation.

 

FE Na		% fraction percent rate ratio
Decimal Precision   0 1 2 3

 

Data action

 
     
 
Include literature references: Yes   No

 

 

Notes

• The FENa helps differentiate acute tubular necrosis from a prerenal state.
• FENa >2 % usually indicates ATN.
• FENa <1% usually indicates a prerenal state such as dehydration or other forms of prerenal azotemia.
• FENa's between 1% and 2% may be seen with either ATN or prerenal state.

 
Equations used
 

FENa = (UrineNa / SerumNa) / (UrineCr / SerumCr) * 100

 

 

References

1. Stein JH, ed. Internal Medicine. 4th edition. Mosby-Year Book. 1994. NLMN ID: 9309759

 

Associated Logical Observation Identifiers Names and Codes [LOINC]
 

Parameter	LOINC's and Suggested Units
Urine Na	2955-3 : mEq/L      35678-2 : mEq/L      2955-3 : mmol/L      35678-2 : mmol/L
Serum Na	2951-2 : mmol/L      2947-0 : mEq/L      32340-2 : mEq/L      39791-9 : mEq/L
Urine Cr	35674-1 : mg/dL      2161-8 : mg/dL      14683-7 : mmol/L
Serum Cr	2160-0 : mg/dL      38483-4 : mg/dL      14682-9 : mcmol/L      22726-4 : mcmol/L      59826-8 : mcmol/L
FE Na	49135-7 : %

 
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