Total Carbon Dioxide (Total CO₂) in Blood Gas Analysis (Periodic Report)
This test measures the amount of carbon dioxide dissolved in your blood, which helps assess how well your body is balancing acidity and alkalinity (pH) and how efficiently your lungs are removing waste gases.
Your blood’s CO₂ levels help determine lung function and acid-base balance.
Key facts at a glance
- LOINC
- 60790-3
- Short code
- CO2 gas del.total RptPeriod Vol Gas DS
- Synonyms
- CO2 gas del.total RptPeriod Vol Gas DS
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Ref low
- 22
- Ref high
- 28
- Critical range
- — – 5 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- CPT
- 82374
- SNOMED
- 396252006
- Specimen volume
- 5 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
Why Is This Test Done?
Doctors may order this test if you have symptoms like shortness of breath, chest pain, rapid heartbeat, or signs of respiratory or metabolic issues. It’s also used to monitor conditions like chronic obstructive pulmonary disease (COPD), heart problems, or kidney disease.
What Does It Measure?
Total CO₂ reflects the combined amount of dissolved CO₂ in your blood, which includes carbonic acid (formed when CO₂ reacts with water) and bicarbonate ions (the primary way your body regulates acidity). This helps evaluate how well your lungs and kidneys work together to maintain healthy blood chemistry.
Sample Collection and Preparation
A blood sample is drawn from a vein (usually in your arm) and sent to a lab. The test measures CO₂ levels in whole blood or plasma, often as part of a broader blood gas analysis that also checks oxygen and pH levels.
What Are Common Causes of Abnormal Results?
High CO₂ levels (hypercapnia) may occur with lung diseases (e.g., COPD), heart failure, or conditions that slow breathing. Low CO₂ levels (hypocapnia) can result from hyperventilation (e.g., anxiety, asthma) or overventilation during anesthesia.
Reference range
Adult: 22-28 mmol/LN/A
Inform your healthcare provider if you are taking blood thinners. No special preparation required.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
This test is critical for diagnosing and managing acid-base imbalances, respiratory disorders, and metabolic conditions. By comparing CO₂ levels to pH and oxygen measurements, doctors can pinpoint whether a problem lies in your lungs (respiratory cause) or kidneys (metabolic cause) and guide treatment decisions, such as oxygen therapy or medication adjustments.
Short name
Total CO₂ Blood Gas
Frequently asked questions
How often is this test repeated?
What does a ‘periodic report’ imply about the test results?
Can I fast before this test?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy