Skip to content

Serum Oxygen Saturation (SaO₂) by Pulse Oximetry

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

This test measures how much oxygen is bound to hemoglobin in your blood, typically assessed using a finger probe. It reflects your oxygen levels in arterial blood.

Quick summary

["SaO₂ helps doctors check if your lungs are effectively delivering oxygen to your body."]

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

Key facts at a glance

LOINC
8851-8
Short code
SaO2 % PA-L
Synonyms
SaO2 % PA-L
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

What Is SaO₂ Used For?

SaO₂ is commonly used during and after medical procedures, in hospital settings, or when monitoring conditions like heart or lung disease. It’s also part of routine check-ups for patients with chronic respiratory issues.

How Is SaO₂ Measured?

SaO₂ is measured using a pulse oximeter—a small device placed on your finger. It sends light through your blood vessels to estimate oxygen saturation levels.

Normal vs. Abnormal Results

While reference ranges vary by lab, typical SaO₂ values range from 95% to 100% in healthy individuals. Lower values may indicate reduced oxygen delivery, which could signal lung problems or other health concerns.

Common Conditions Affecting SaO₂

Low SaO₂ can occur with conditions like asthma, COPD, pneumonia, or heart failure. High SaO₂ alone isn’t usually concerning unless paired with symptoms like shortness of breath.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

SaO₂

Frequently asked questions

Why might my SaO₂ test be done during a hospital stay?
Your SaO₂ test may be part of ongoing monitoring, especially if you have a condition affecting oxygen levels, like heart or lung disease. It helps doctors track how well your body is responding to treatment or changes in your condition.
Can SaO₂ be affected by movement or skin tone?
Yes, movement or nail polish can interfere with pulse oximeter readings. Dark skin tones may also slightly affect accuracy, so doctors may use additional methods if needed.
Is SaO₂ the same as blood oxygen levels measured in a lab?
No, SaO₂ is an indirect estimate using a pulse oximeter, while lab tests (like arterial blood gases) measure actual oxygen content in blood. Both serve different purposes in medical care.
  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