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Lab Dept:
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Urine/Stool
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Test Name:
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FENA
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General Information
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Lab Order Codes:
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FENA
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Synonyms:
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Sodium, Fractional Excretion; Fractional Excretion of Sodium
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CPT Codes:
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82565 – Creatinine, blood
82570 – Creatinine, other source
84295 – Sodium, serum
84300 – Sodium, urine
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Test Includes:
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Plasma Sodium concentration in mEq/L, Urine Sodium concentration in mEq/L, Plasma Creatinine concentration in mg/dL, Urine Creatinine in mg/dL
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Logistics
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Test Indications:
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Useful in defining the extent of sodium conservation by the kidneys. It may also help identify certain diseases of the kidney.
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Lab Testing Sections:
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Chemistry
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Phone Numbers:
Minneapolis:
Saint Paul:
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612-813-6280
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651-220-6550
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Test Availability:
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Daily, 24 hours
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Turnaround Time:
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1 day
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Special Instructions:
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A urine specimen should be collected at the same time or as close as possible to the time of plasma/serum collection.
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Specimen
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Specimen Type:
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Plasma/Serum and Urine, random
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Container:
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Serum/Plasma: Green top tube (Lithium Heparin) or red top tube (plain, no gel)
Urine: Plastic leakproof container (No preservatives)
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Draw Volume:
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0.6 mL blood and 1 -3 mL random urine
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Processed Volume:
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0.2 mL plasma/serum and 0.5 mL urine
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Collection:
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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.
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Special Processing:
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N/A
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Patient Preparation:
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None
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Sample Rejection:
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Mislabeled or unlabeled specimens
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Interpretive
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Reference Range:
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Expected value: 1 – 3%
Prerenal Azotemia: <1.0%
Acute Tubular Necrosis: >3.0%
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Critical Values:
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N/A
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Limitations:
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Certain diuretic medicines may affect test results.
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Methodology:
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Alkaline Picrate/Kinetic; Integrated Multisensor Technology
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References:
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Burtis, CA, Ashwood, ER (1999) Tietz Textbook of Clinical Chemistry, 3rd Edition, W.B. Saunders Co. 1999, pp 1057-1058
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Medline Plus Health Information, www.nlm.nih.gov/medlineplus
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Jacobs & DeMott Laboratory Test Handbook (2001) Lexi-Comp, Inc, Hudson, OH, 5th Edition
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