Lab Dept:


Test Name:


General Information

Lab Order Codes:



Sodium, Fractional Excretion; Fractional Excretion of Sodium

CPT Codes:

82565 – Creatinine, blood
82570 – Creatinine, other source
84295 – Sodium, serum
84300 – Sodium, urine

Test Includes:

Plasma Sodium concentration in mEq/L, Urine Sodium concentration in mEq/L, Plasma Creatinine concentration in mg/dL, Urine Creatinine in mg/dL


Test Indications:

Useful in defining the extent of sodium conservation by the kidneys. It may also help identify certain diseases of the kidney.

Lab Testing Sections:


Phone Numbers:

MIN Lab: 612-813-6280

STP Lab: 651-220-6550

Test Availability:

Daily, 24 hours

Turnaround Time:

1 day

Special Instructions:

A urine specimen should be collected at the same time or as close as possible to the time of plasma/serum collection. The plasma/serum must be collected within 48 hours of the urine specimen.


Specimen Type:

Plasma/Serum and Urine, random


Serum/Plasma: Green top tube (Lithium Heparin) or SST (gold, marble or red top tube)

Urine: Plastic leak proof container (No preservatives)

Draw Volume:

0.6 mL blood and 1 -3 mL random urine

Processed Volume:

0.2 mL plasma/serum and 0.5 mL urine


A random urine sample may be obtained by voiding into a urine cup and is often performed at the laboratory. Bring the refrigerated container to the lab. Make sure all specimens submitted to the laboratory are properly labeled with the patient’s name, medical record number and date of birth.

Special Processing:


Patient Preparation:

Eat a normal diet with a normal amount of salt. Certain diuretic medications may affect results.

Sample Rejection:

Mislabeled or unlabeled specimens


Reference Range:

Expected value: 1 – 3%

Prerenal Azotemia: <1.0%

Acute Tubular Necrosis: >3.0%

Critical Values:



See Patient Preparation


Enzymatic Creatinine/Indirect Multi-sensor Sodium


Burtis, CA, Ashwood, ER (1999) Tietz Textbook of Clinical Chemistry, 3rd Edition, W.B. Saunders Co. 1999, pp 1057-1058

Medline Plus Health Information,

Jacobs & DeMott Laboratory Test Handbook (2001) Lexi-Comp, Inc, Hudson, OH, 5th Edition


7/14/2014: Method update, previously listed as Alaline Picrate/Kinetic/Integrated Multisensor Technology