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Test Code CO2 Carbon Dioxide

Specimen and Container/Tube

Specimen Type: Plasma

Preferred Specimen: Li-Heparin Mint Green Top

Other Acceptable specimens: Serum/Gold Top, Serum/Red Top

Specimen Handling and Transport Instructions

UCMC Onsite Instructions: 

Collect specimen per standard collection procedure and send to laboratory immediately. 

 

UCMC Offsite and UC MedLab Outreach Instructions: 

  • Samples should be centrifuged within 2 hours of collection.
  • Centrifuge specimens at >2500 x g for 10 minutes at room temperature.
  • Aliquot sample into plastic transport tube containing a minimum of 0.2 mL of specimen.
  • Make sure sample is tightly capped.
  • Samples must be sent room temperature at 15-25oC.

Rejection Criteria

  • Common specimen rejected situations include: incorrect specimen type, insufficient volume, missing or incomplete specimen identifiers, incorrect specimen transport, or specimens outside stability limits. 
  • Specimens that are clotted or grossly hemolyzed.
  • Specimens that were transported unspun/whole blood and draw time is greater than 6 hours.

Reference Values

 

Test

Age

Sex

Reference Range

Carbon Dioxide

All

All

23-30 mmol/L

Anion Gap

All

All

6-15 mmol/L

Critical Values

Analyte

Unit

Low

High

Age

Carbon Dioxide

mmol/L

<10

>40

All

CPT Codes

82374

LOINC Codes

2028-9

Volume

Preferred Volume: 0.5 mL

Minimum Volume: 0.2 mL

Specimen Stability

Storage Temperature

Stability

Room temperature

7 days

Refrigerated

40 hours

Frozen

6 months

Collection Instructions

Collect specimen per standard laboratory collection procedures. 

 

Test Components

Carbon Dioxide

Anion Gap (IGAP) is a calculation of Sodium (Na+ ) minus ((Cl-) plus the Bicarbonate (CO2))

Clinical Indications

The bicarbonate content of serum or plasma is a significant indicator of electrolyte dispersion and anion deficit.

Methodology

Enzymatic Method (Roche Diagnostics)

Additional Information

  • Results should always be assessed in conjunction with patient's medical history, clinical examination and other findings.
  • The concentration of CO2 in serum or plasma is one of the principal determinants of blood pH, since the bicarbonate buffer system is quantitatively very important for the maintenance of blood pH.
  • CO2 measurements are necessary for the classfication and differential diagnosis of acid/base disorders.
  • Bicarbonate content in uncapped tubes decreases by approximately 4 mmol/L after one hour.
  • Also included in Basic Metabolic Panel KPNL, Comprehensive Metabolic Panel CPNL, ER Panel I STKG, Renal Function Panel RPNL, CMP for chronic lymphocytic leukemia (CPNL FOR CLL PATIENTS ONLY) SSTCP, BMP for chronic lymphocytic leukemia (KPNL FOR CLL PATIENTS ONLY)  SSTKP and Electrolyte Panel LYTS 

Turnaround Time

Turnaround times are relative to the time the specimen is received in the test laboratory. 

 

STAT Turnaround Time: 1 hour

Routine Turnaround Time: 4 hours

Testing Schedule: 24/7

Synonyms/Keyword Search

CO2, HCO3, Bicarbonate

Last Review Date

8/19/2024

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