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Test Code FRACEXNA Fractional Excretion of Sodium, Urine

Additional Codes

  • Expanse Test Name: Fractional Excretion NA, U Rand 
  • Medinet Ref Code: FRACEXNA
  • OV Code: LAB*FRACEXNA

Methodology

Creatinine is measured via kinetic Jaffe reaction.

Sodium is measured using V-LYTE multisensor Technology

Specimen Requirements

Please submit both a urine and a serum or plasma sample.

 

Urine

Submit 10 mL of urine from a random collection, refrigerated.

 

Serum or plasma:

Collect specimen in a green-top (lithium heparin), or yellow top (serum, SST), tube.  Spin down and send 1.0 mL serum or plasma, refrigerated. The blood sample should be collected within 2 hours of the urine sample.

 

Unspun specimens must be transported at ambient temperature and should arrive to the laboratory within one hour of draw.

Reference Values

<1% -Prerenal failure

>1.5%- Acute tubular necrosis

Test Classification and CPT Coding

84295- Sodium

82565-Creatinine

Useful For

Differentiating prerenal failure from postischemic and nephrotxic acute renal failure.