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  Fractional Excretion of Sodium (FENa)

 
Input
 
Urine Na  
Serum Na  
Urine Cr  
Serum Cr  

 
Result
 
Important: Inputs must be complete to perform calculation.

 
 
FE Na  
 
Decimal Precision  
 

 
  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 NCBI Logo

 
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 : %      

 
This material contains content from LOINC (http://loinc.org). LOINC is copyright © 1995-2023, Regenstrief Institute, Inc. and the Logical Observation Identifiers Names and Codes (LOINC) Committee and is available at no cost under the license at http://loinc.org/license. LOINC® is a registered United States trademark of Regenstrief Institute, Inc.

 
Associated ICD10-CM Codes
 
   N17.2Acute kidney failure with medullary necrosis
   N19Unspecified kidney failure
   N25.9Disorder resulting from impaired renal tubular function, unspecified
   N17.9Acute kidney failure, unspecified

 
Associated ICD9-CM Codes
 
   276.5Hypovolemia
   584.9Acute renal failure nos
   588.8Impaired renal funct nec
   588.9Impaired renal funct nos
   586Renal failure nos
   583.7Nephr nos/medull necros

 

 
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