Oxygen Saturation in Whole Blood (SaO₂)
This test measures how much oxygen is bound to hemoglobin in your red blood cells, expressed as a percentage. It helps assess your body’s ability to deliver oxygen to tissues.
["A key indicator of oxygen levels in your blood, useful for diagnosing or monitoring lung, heart, or blood disorders."]
Key facts at a glance
- LOINC
- 68363-1
- Short code
- SaO2 % BldCo
- Synonyms
- SaO2 % BldCo
- Category
- chemistry
- Sample
- whole-blood
- Container
- Lavender-top (EDTA)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Specimen volume
- 3 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 4–24 hours
- Order
- routine
What This Test Measures
Your blood carries oxygen from the lungs to every part of your body. This test specifically looks at the percentage of hemoglobin molecules that are saturated with oxygen (SaO₂). For example, a normal value might reflect efficient oxygen transport, while lower values could signal issues like poor lung function or anemia.
Why It’s Done
Doctors may order this test to evaluate conditions like lung diseases (e.g., COPD), heart problems, or blood disorders. It’s also used during surgeries, anesthesia, or in critical care settings to monitor oxygen levels in real time.
Sample Collection and Process
A small blood sample is taken from your arm or finger. The blood is analyzed immediately or sent to a lab where oxygen saturation is measured using a method that detects the light absorbed by oxygenated versus deoxygenated hemoglobin.
Normal vs. Abnormal Results
Results are typically reported as a percentage (e.g., 95–100% for healthy adults at rest). While reference ranges can vary slightly by lab, consistently low values (below 90%) may warrant further investigation, especially if you experience symptoms like shortness of breath.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Low SaO₂ levels can indicate serious conditions such as hypoxia (lack of oxygen), where tissues aren’t receiving enough oxygen. This may point to lung diseases (e.g., pneumonia, emphysema), heart failure, or other systemic issues. High values (rarely seen in healthy individuals) might suggest polycythemia (excess red blood cells) or other rare conditions.
Short name
Oxygen Saturation
Frequently asked questions
What causes abnormal oxygen saturation?
How often should I get this test?
Can diet or supplements affect oxygen saturation?
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