Oxygen Content in Arterial Blood (Partial Pressure of Oxygen in Arterial Blood)
This test measures the amount of oxygen dissolved in your blood from an artery, often checked to assess lung function or oxygen levels in the bloodstream.
["Helps doctors evaluate how well your lungs are delivering oxygen to your blood and identify potential breathing or lung issues."]
Key facts at a glance
- LOINC
- 10232-7
- Short code
- O2 Ct AO root-sCnc
- Synonyms
- O2 Ct AO root-sCnc
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- 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 if you have symptoms like shortness of breath, fatigue, or if you’re at risk for lung conditions (e.g., asthma, COPD, pneumonia). It can also be used during surgeries, before or after certain treatments, or to monitor chronic health conditions like heart or lung disease.
How Is the Test Performed?
A small sample of blood is taken from an artery in your arm or wrist using a needle. The blood is then analyzed in a lab to measure the oxygen pressure.
What Are Common Results?
Results are typically reported in millimeters of mercury (mmHg). Lower-than-expected levels may indicate lung problems, while higher-than-expected levels could suggest conditions like high altitude exposure or certain heart conditions.
What Might Affect Results?
Factors like smoking, recent exercise, breathing difficulties, or certain medications (e.g., asthma inhalers) can influence your oxygen levels. Avoid smoking or heavy exercise 24 hours before the test.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
This test plays a key role in diagnosing and managing conditions affecting oxygen exchange in the body. Low PaO₂ can signal lung diseases, sleep apnea, or other respiratory disorders, while elevated levels may warrant further investigation into conditions like polycythemia (increased red blood cells).
Short name
Arterial Oxygen Pressure (PaO₂)
Frequently asked questions
Why do doctors sometimes take blood from an artery instead of a vein?
How soon will I get my results, and what should I do next?
Can I eat or drink 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