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Test Code LAB9571 Potassium, Whole Blood

Performing Laboratory

St. Louis Children's Hospital Laboratory  - Core Lab

Specimen Requirements

Patient Preparation: None

Collection Container/Tube:

Preferred: Air-tight balanced heparinized blood gas syringe

Acceptable: Heparinized Capillary blood gas tube or green microtainer

Submission Container/Tube: May not be received from outside facility

Specimen Collection Volume: 1.0 mL (minimum 0.3 mL)

Special Instructions: Mix well and send to lab immediately. If collecting in capillary blood gas tube be sure to add flea to mix.

 

Sample Rejection

Mislabled or unlabeled specimens 

Clotted specimens

Logistics

Test Availability: Monday-Sunday

Cut-off time: None, performed as received

Turnaround Time: Same Day; 30 minutes from receipt in lab

Reference Values

Reference Interval: 

All ages: 3.3-4.9 mmol/L                                                                  

Critical Value: 

<1 year: <2.5 mmol/L  OR  >7.0 mmol/L                                                            
≥ 1 year: <2.5 mmol/L  OR  >6.5 mmol/l

Critical results will be called back automatically initially and every 24 hours thereafter.

Methodology

Ion-Selective Electrode (ISE)

Limitations

  • Unable to access hemolysis in whole blood specimens.
  • In vitro hemolysis causes falsely elevated potassium.

Additional Information

FOR SLCH CORE LABORATORY USE ONLY

Lab Processing Instructions: DO NOT SPIN. give specimen directly to blood gas bench

Processed Volume: 1.0 (minimum 0.3 mL) whole blood

Analyte Stability:

Specimen Type Temperature Time
Whole Blood (unprocessed)  Ambient 2 hours
Plasma/Serum (processed) Refrigerated      not acceptable   
  Ambient  not acceptable
  Frozen  not acceptable   

 

Test Classification and CPT Code

84132

LOINC

2823-3

Last Reviewed

07/2025