Oxygen Saturation in Whole Blood (via Pulse Oximetry)
This test measures the percentage of hemoglobin in your blood that is bound to oxygen, helping assess how well oxygen is being delivered to your body’s tissues.
["Your oxygen levels help doctors check for breathing problems or low blood oxygen, which can affect energy and overall health."]
Key facts at a glance
- LOINC
- 71843-7
- Short code
- SaO2 DF BldA from pO2
- Synonyms
- SaO2 DF BldA from pO2
- Category
- chemistry
- Sample
- whole-blood
- Container
- Lavender-top (EDTA)
- Units
- N/A
- Ref low
- 80
- Ref high
- 100
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- calculated-from-oxygen-partial-pressure
- 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
Oxygen saturation (SpO₂) reflects the proportion of oxygen molecules attached to red blood cells. A device called a pulse oximeter—worn on a finger or toe—uses light to measure this percentage. Normal values can vary slightly by age and health status, but levels below 90% may signal concern.
How It’s Done
No special preparation is needed. A small sensor is placed on your finger or toe, and it sends light through your blood vessels to measure oxygen saturation. Results are usually available within minutes.
Common Uses
Doctors use this test to monitor breathing issues (e.g., asthma, COPD), check for low oxygen during surgery or illness, or evaluate heart or lung function in patients with symptoms like shortness of breath or fatigue.
Possible Results & Next Steps
Low oxygen saturation (below 90%) may prompt further testing, like a blood gas analysis or consultation with a specialist. High levels (above 100%) are rare but could indicate conditions like polycythemia (too many red blood cells).
Reference range
NCBI: PaO2 80-100 mmHgN/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.
Oxygen saturation is critical for diagnosing or monitoring conditions affecting the lungs (e.g., pneumonia, emphysema), heart (e.g., heart failure), or circulation. Chronic low levels may indicate long-term health risks, such as organ damage or fatigue-related issues.
Short name
None
Frequently asked questions
Why might my doctor order this test?
What do my results mean?
Can I do anything to improve my oxygen levels?
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 17, 2026. · Read our editorial policy