Carbon Dioxide in Blood (Total, Dissolved)
This test measures the amount of carbon dioxide dissolved in your blood, which helps assess how well your body is balancing acidity and alkalinity (acid-base balance). It’s often part of a broader blood gas evaluation.
["Your blood’s carbon dioxide levels help determine if your body is maintaining proper pH balance, especially important for breathing and kidney function."]
Key facts at a glance
- LOINC
- 53090-7
- Short code
- CO2 Fld.NB-sCnc
- Synonyms
- CO2 Fld.NB-sCnc
- 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 This Test Is Done
Doctors may order this test if you have symptoms like shortness of breath, rapid breathing, chest pain, confusion, or signs of acid-base imbalance. It’s also used in monitoring conditions like chronic obstructive pulmonary disease (COPD), kidney disease, or metabolic disorders.
What to Expect Before the Test
No special preparation is needed. You’ll typically have a small needle inserted into your arm or vein to draw blood. If you’re having a blood gas test (often for arterial blood), you may need to sit still for a few minutes to avoid stressing your blood vessels.
What the Results Mean
Results help determine if your blood is too acidic or alkaline (metabolic acidosis or alkalosis) or if your lungs aren’t removing enough carbon dioxide (respiratory issues). Abnormal results may signal conditions like kidney problems, heart failure, or respiratory disorders.
Common Conditions Linked to Abnormal Results
High levels may indicate metabolic alkalosis or conditions like dehydration or overuse of diuretics. Low levels can suggest respiratory alkalosis, hyperventilation, or kidney issues. Always discuss results with your healthcare provider.
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.
This test is critical for diagnosing and managing acid-base imbalances, respiratory disorders, and metabolic conditions. It helps guide treatment plans, such as adjusting medications, managing breathing support, or addressing fluid/electrolyte imbalances.
Short name
Total CO₂ (blood gas)
Frequently asked questions
What does a ‘normal’ result mean for me personally?
Can I eat or drink before this test?
How long will it take to get my results?
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