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Carbon Dioxide (Plasma/Serum) Concentration (Arbitrary Units)

Published: August 9, 2026Updated: August 16, 2026

This test measures the amount of carbon dioxide in your blood plasma or serum, often used to assess how well your body is balancing gases and maintaining acid-base balance.

Quick summary

["Helps evaluate blood chemistry and acid-base balance."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
74684-2
Short code
CO2 p dialysis SerPl-sCnc
Synonyms
CO2 p dialysis SerPl-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 Is This Test Done?

Your healthcare provider may order this test to check for conditions affecting how your body regulates carbon dioxide, such as respiratory issues, metabolic disorders, or kidney function. It can also be part of broader blood chemistry evaluations, including those for acid-base imbalances or during dialysis monitoring.

What Does the Result Indicate?

High or low carbon dioxide levels can signal problems like hyperventilation, lung disease, or metabolic acidosis. In dialysis patients, it may reflect how well your system is removing waste products or maintaining fluid balance.

How Is the Test Performed?

A small blood sample is drawn from a vein, usually in your arm. The sample is then sent to a lab for analysis using a specialized method to measure carbon dioxide concentration in plasma or serum.

What Are Common Causes?

Causes of abnormal results may include breathing disorders (e.g., hyperventilation or chronic obstructive pulmonary disease), kidney problems, or conditions affecting fluid balance. In dialysis patients, it could relate to dialysis efficiency or electrolyte imbalances.

Reference range

Adult: 22-28 mmol/LN/A

Specimen: serum

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.

◆Associated findings1

Short name

CO₂ Level

Frequently asked questions

What does a normal result mean for me?
A normal result suggests your body is maintaining a balanced level of carbon dioxide in your blood, which is important for normal pH and overall health. However, results can vary based on your medical condition and other factors, so discuss any concerns with your provider.
Can diet or lifestyle affect this test?
Dietary habits, such as high protein or high-fat meals, may temporarily influence blood chemistry, including carbon dioxide levels. Avoiding heavy meals before testing can help ensure more accurate results. Lifestyle factors like exercise or stress may also play a role, so follow your provider’s specific instructions.
How often should I get this test?
The frequency depends on your health condition. If you’re undergoing dialysis or have a chronic respiratory or metabolic disorder, your provider may recommend regular monitoring. Follow their guidance to determine the best schedule for you.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

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.

Medical Disclaimer

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