Lab Dept:


Test Name:

CO2 Total

General Information

Lab Order Codes:



Bicarb, Bicarbonate, Carbon Dioxide, Total; CO2

CPT Codes:

82374 – Carbon dioxide (bicarbonate)

Test Includes:

CO2 concentration in mEq/L. Total CO2 is also included in the following panels: Electrolyte Panel, Basic Metabolic Panel, Comprehensive Metabolic Panel, Renal Panel


Test Indications:

Useful for evaluation of acid-base balance and the body’s ability to control pH. Bicarbonate ion is the principle transport form for CO2.

Lab Testing Sections:


Phone Numbers:

MIN Lab: 612-813-6280

STP Lab: 651-220-6550

Test Availability:

Daily, 24 hours

Turnaround Time:

30 minutes

Special Instructions:



Specimen Type:

Whole blood


Preferred: Green top (Li Heparin) tube
Alternate: Red, marble or gold top tube

Draw Volume:

0.6 mL blood

Processed Volume:

0.2 mL plasma/serum


Collect sample anaerobically to minimize exposure to air for TCO2.

Special Processing:

Lab Staff: Centrifuge specimen, remove serum/plasma aliquot into plastic sample cup. Analyze sample immediately or store at refrigerated temperatures. Once the sample is opened (uncapped), the sample must be processed within 1 hour for TCO2.

Patient Preparation:


Sample Rejection:

Mislabeled or unlabeled specimens; sample submitted in incorrect tube


Reference Range:

18 - 26 mEq/L

Critical Values:

<10 or >40 mEq/L


● CO2 decreases when uncapped specimens are exposed to air.|
● Underfilling of vacutainer collection tubes may decrease CO2 results by as much as 3 mEq/L.


Enzymatic Carbonate


ECO2 Flex® reagent cartridge insert sheet Part number 717137.101 Version F (2008-06-09)  

Dimension RxL MAX Operator’s Guide (05/2003)

Tietz Textbook of Clinical Chemistry (1999) 3rd Edition, W.B. Saunders Company

Clinical Significance, Dade Behring Inc., Glasgow Business Community, Mailbox 531, P.O. Box 6101, Newark, Delaware 19714

Jacobs & DeMott Laboratory Test Handbook (2001) Lexi-Comp, Inc, Hudson, OH, 5th Edition, 2001


2/14/2005: Critical values previously listed as <10 to >35 mEq/L.
8/19/2009: Turnaround time previously listed as 2 hours.
4/24/2013: Conversion to enzymatic CO2 on backup instruments.
2/9/2016: Update alt tube type