Clinics and Departments

Laboratory Services

Lab Dept:

Urine/Stool

Test Name:

FENA

General Information

Lab Order Codes:

FENA

Synonyms:

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

Logistics

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:

Chemistry

Phone Numbers:

Minneapolis:

Saint Paul:

 

612-813-6280

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.

Specimen

Specimen Type:

Plasma/Serum and Urine, random

Container:

Serum/Plasma: Green top tube (Lithium Heparin) or red top tube (plain, no gel)

Urine: Plastic leakproof 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

Collection:

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:

N/A

Patient Preparation:

None

Sample Rejection:

Mislabeled or unlabeled specimens

Interpretive

Reference Range:

Expected value: 1 – 3%

Prerenal Azotemia: <1.0%

Acute Tubular Necrosis: >3.0%

Critical Values:

N/A

Limitations:

Certain diuretic medicines may affect test results.

Methodology:

Alkaline Picrate/Kinetic; Integrated Multisensor Technology

References:

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

Medline Plus Health Information, www.nlm.nih.gov/medlineplus

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



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