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Test Code LAB122 Sodium, Plasma

Performing Laboratory

St. Louis Children's Hospital Laboratory - Chemistry

Specimen Requirements

Note: This test is also available as part of LAB17, Comprehensive Metabolic Panel (CMP); LAB15, Basic Metabolic Panel (BMP); LAB16, Electrolyte Panel Lytes Pnl); and LAB19, Renal Function Panel. See Common Panel Test Combinations to avoid duplicate requests if needed.

 

Patient Preparation: None

Collection Container/Tube:

Preferred: Mint green-top Lithium Heparin (MNTGRN LiHep) tube

Acceptable: Green samplette/microtainer, plain red-top tube, or Gold SST gel tube

Submission Container/Tube: If specimen is coming from outside facility and collected in a microtainer or plain red-top tube aliquot processed sample into a plastic vial for transport (labeling with specimen type).

Specimen Collection Volume: 1.0 mL (minimum 0.6 mL)

Special Instructions: None

Sample Rejection

Mislabled or unlabeled specimens

Logistics

Test Availability: Monday-Sunday

Cut-off time: None, performed as received

Turnaround Time: Same Day; 2 hours from receipt in lab

Reference Values

Reference Interval: 

Plasma (all ages) 135-145 mmol/L                                                                  

Critical Value: 

all ages: <120  OR  >160 mmol/L                                                            

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

 

Methodology

Ion-Selective Electrode (ISE)

Limitations

  • NA

Additional Information

FOR SLCH CORE LABORATORY USE ONLY

Lab Processing Instructions: Centrifuge to separate. If specimen is collected in microtainer or plain red-top tube aliquot sample into a Roche false-bottom tube for testing (labeling aliquot with specimen type).

Processed Volume: 0.3 mL plasma/serum

Analyte Stability: 

Specimen Type Temperature Time
Whole Blood (unprocessed)  Ambient 24 hours
Plasma/Serum (processed) Refrigerated (preferred) 7 days   
  Ambient  4 days
  Frozen  6 months    

 

Test Classification and CPT Code

84295

LOINC

2951-2

Last Reviewed

06/2025