Carbon Dioxide (Total) in Blood Gas Analysis
This test measures the amount of carbon dioxide 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 gas CO₂ levels help doctors check lung function and acid-base balance."]
Key facts at a glance
- LOINC
- 60924-8
- Short code
- CO2 during insp VFr/PPres Away adap
- Synonyms
- CO2 during insp VFr/PPres Away adap
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Ref low
- 22
- Ref high
- 28
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- CPT
- 82374
- 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 It Matters in Your Health
CO₂ in your blood is produced during normal metabolism and exhaled by your lungs. Abnormal levels can indicate issues like poor lung function, fluid overload, or metabolic problems. This test is often part of a broader blood gas evaluation, especially if you have symptoms like shortness of breath, rapid breathing, or fatigue.
When You Might Need This Test
Your healthcare provider may order this test if you have symptoms like difficulty breathing, chest pain, confusion, or rapid heartbeat. It’s also used before surgeries, during intensive care, or if you have conditions like heart failure, kidney disease, or respiratory infections.
What to Expect During the Test
A small blood sample is taken from a vein, usually in your arm. The blood is analyzed immediately or sent to a lab to measure CO₂ levels, often alongside oxygen and pH. The process takes a few minutes and is generally painless.
Possible Results and Next Steps
Results are compared to standard ranges to identify imbalances. If your levels are too high or too low, your doctor may recommend further tests or treatments, such as breathing exercises, medications, or adjustments to your condition management plan.
Reference range
Adult: 22-28 mmol/LN/A
No special preparation usually required. Stay well hydrated. Inform your healthcare provider of all medications and supplements you are taking.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
High CO₂ levels (hypercapnia) can cause respiratory acidosis, leading to symptoms like headache, confusion, or even coma in severe cases. Low CO₂ levels (hypocapnia) may indicate overbreathing or lung hyperinflation. Monitoring CO₂ helps doctors diagnose and treat conditions like chronic obstructive pulmonary disease (COPD), asthma, or metabolic disorders.
Short name
Total CO₂ (Blood Gas)
Frequently asked questions
What does a high or low CO₂ level mean?
What if my CO₂ level is outside the normal range?
Does this test require fasting?
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