Lab Test

Sodium and Potassium

Na/K (Sodium and Potassium)

Test Codes

Antrim #17101, EPIC: LAB5114, NAK

Instructions

NOTE: Blood should be obtained with as little venous stasis (i.e. tourniquet time) as possible. Fist clenching may result in false elevation of potassium.

Specimen Collection Criteria

FOR EC AND INPATIENT SAMPLE COLLECTION ONLY:

Preferred Sample:  One Light Green (Mint) Top or Dark Green with Yellow Ring Top Plasma Separator Tube (PST).  Minimum Whole Blood: 4.0 mL

FOR OUTREACH/OUTPATIENT SAMPLE COLLECTION ONLY:

Collect: One Gold-top SST tube. (Minimum Whole Blood: 4.0 mL)

Contact Laboratory for acceptability of other tube types.
See Minimum Pediatric Specimen Requirements for Microtainer® collection.

Caution: Never refrigerate collection tube prior to centrifugation. This may cause a falsely elevated potassium. 

Physician Office/Draw Specimen Preparation

Let SST specimens clot 30-60 minutes then immediately centrifuge to separate serum from cells. Refrigerate (2-8°C or 36-46°F) the centrifuged SST tube within two hours of collection. (Minimum: 0.5 mL)

Preparation for Courier Transport

Transport: Centrifuged SST tube, refrigerated (2-8°C or 36-46°F). (Minimum: 0.5 mL)

Rejection Criteria

  • Moderate to grossly hemolyzed specimens.
  • Inadequately centrifuged Microtainers® or Gold-top tubes.
  • Red-top tubes with serum not separated from cells within two hours of collection.

In-Lab Processing

Let SST specimens clot 30-60 minutes. Centrifuge SST tubes or Microtainers® to separate serum from cells. Deliver immediately to the appropriate testing station.


Storage

Specimen Stability for Testing:

Centrifuged SST Tubes and Microtainers® with Separator Gel
Room Temperature (20-26°C or 68-78.8°F): 2-4 hours
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): Unacceptable

Red-top Tubes and Microtainers® without Separator Gel
Room Temperature (20-26°C or 68-78.8°F): 2-4 hours
Refrigerated (2-8°C or 36-46°F): Unacceptable
Frozen (-20°C/-4°F or below): Unacceptable

Serum Specimens (Pour-Overs)
Room Temperature (20-26°C or 68-78.8°F): 2-4 hours
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): 7 days

Specimen Storage in Department Prior to Disposal:

Refrigerated (2-8°C or 36-46°F): 7 days

Laboratory

Canton Chemistry Laboratory
Dearborn Chemistry Laboratory
Farmington Hills Chemistry Laboratory 
Grosse Pointe Chemistry Laboratory 
Royal Oak Automated Chemistry Laboratory 
Troy Chemistry Laboratory
Taylor Chemistry Laboratory
Trenton Chemistry Laboratory
Wayne Chemistry Laboratory 

Performed

Sunday – Saturday, 24 hours a day.
STAT results available within 1 hour of receipt in the Laboratory.
Routine results available within 4 hours.

Reference Range

See individual Sodium and Potassium assays for reference ranges.

Test Methodology

Potentiometric.

Interpretation

See individual Sodium and Potassium assays for interpretation..

Clinical Utility

See individual Sodium and Potassium assays for clinical utility.

CPT Codes

84295, 84132.
LOINC:  Potassium 2823-3

Contacts

Last Updated

7/19/2021

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