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Respiratory CO₂ Production Rate (from expired breath)

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

This test measures how much carbon dioxide (CO₂) your body releases through your breath during a short period, often used to assess lung function and metabolic health.

Quick summary

["Helps doctors evaluate breathing efficiency and metabolic balance."]

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

Key facts at a glance

LOINC
60825-7
Short code
CO2 production Respiratory
Synonyms
CO2 production Respiratory
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

What Does This Test Measure?

The test quantifies the rate at which CO₂ is produced in your lungs and expelled through exhaled breath. It reflects your body’s respiratory efficiency and metabolic processes, such as how well your lungs oxygenate blood and remove waste gases like CO₂.

Why Might You Need This Test?

Doctors may order this test to diagnose or monitor conditions affecting breathing, such as chronic obstructive pulmonary disease (COPD), asthma, or other lung disorders. It can also help assess metabolic disorders or evaluate responses to treatments.

How Is the Test Performed?

You’ll exhale into a special device that measures CO₂ output over a set time (often 1–3 minutes). The test is quick, painless, and doesn’t require blood or other bodily fluids.

What Does the Result Mean?

Results are compared to standard values for your age, sex, and health status. Abnormal results may indicate inefficient breathing, metabolic issues, or other underlying problems that need further evaluation.

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

Frequently asked questions

What causes abnormal CO₂ production rates?
Abnormal CO₂ production can result from conditions like chronic lung diseases (e.g., emphysema, COPD), respiratory infections, metabolic disorders (e.g., diabetes), or even certain medications. It may also reflect differences in breathing patterns or body composition.
How long does it take to get results?
Results are typically available within 1–2 business days, depending on lab processing times. Your healthcare provider will discuss the findings with you during your follow-up visit.
Can I prepare for this test?
No special preparation is needed. Avoid heavy meals or excessive fluids before testing, as they might affect breathing patterns. Follow any specific instructions your doctor provides.
  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