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Serum or plasma oxygen saturation (SaO₂) measurement

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

This test measures how much oxygen is bound to hemoglobin in your blood, typically drawn from a vein. It helps assess lung function and oxygen delivery to tissues.

Quick summary

["Evaluates lung health and oxygen levels in your blood."]

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

Key facts at a glance

LOINC
28643-5
Short code
SaO2 % BldCoV
Synonyms
SaO2 % BldCoV
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

Why Is This Test Done?

Your healthcare provider may order this test to check for conditions affecting oxygen exchange, such as lung diseases (e.g., COPD, pneumonia), heart problems, or blood disorders. It’s also used during procedures like anesthesia or in cases of suspected low oxygen levels.

What to Expect Before the Test

You’ll likely have a small needle inserted into a vein (usually in your arm). Blood will be drawn into a tube. It takes a few minutes, and you may feel a brief pinch. No special preparation is needed, but inform your provider if you’re on blood thinners.

What Happens During the Test?

The blood sample is analyzed to determine the percentage of hemoglobin saturated with oxygen. Results are compared to standard reference ranges for your age and health status.

What Are Possible Results?

Results show your oxygen saturation level (e.g., 95%–100% is typical for healthy individuals). Low levels may indicate breathing issues, while high levels could suggest conditions like polycythemia (too many red blood cells).

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Oxygen Saturation

Frequently asked questions

How often should I get this test?
Frequency depends on your health condition. Some people get it regularly (e.g., monthly) if they have chronic lung or heart disease, while others may need it only during specific situations (e.g., before surgery). Ask your provider for a personalized schedule.
What do abnormal results mean?
Low oxygen saturation (below 90%) often signals a need for further evaluation, such as imaging tests or pulmonary function tests. High saturation may not always require action but could prompt checks for other conditions like dehydration or blood disorders.
Can I eat or drink before this test?
No special diet is required. You can eat and drink normally unless your provider advises otherwise, especially if you’re scheduled for a procedure that might affect your oxygen levels.
  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