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Oxygen Saturation in Blood (Arterial)

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

This test measures how much oxygen is bound to hemoglobin in your blood from an artery, typically taken from the radial or femoral artery. It helps assess lung function and oxygen delivery to tissues.

Quick summary

["A lower-than-expected SaO₂ level may indicate breathing difficulties or other health concerns."]

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

Key facts at a glance

LOINC
8843-5
Short code
SaO2 % RA.low
Synonyms
SaO2 % RA.low
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 This Test Matters

Measuring arterial oxygen saturation is crucial for diagnosing conditions like chronic obstructive pulmonary disease (COPD), pneumonia, or heart failure. It provides a quick snapshot of how well your lungs are oxygenating your blood.

How the Test Works

A small sample of blood is taken from an artery and analyzed using a device called a pulse oximeter or blood gas analyzer. The test measures the percentage of oxygen-saturated hemoglobin in arterial blood.

When You Might Need It

Your doctor may order this test if you have symptoms like shortness of breath, rapid breathing, or fatigue, especially after a recent illness, surgery, or if you have a known lung or heart condition.

Preparation

No special preparation is needed for this test. You may experience a brief pinch or discomfort from the needle insertion, but it usually goes quickly.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Low arterial oxygen saturation (SaO₂) can signal serious underlying issues, such as severe lung disease, anemia, or even conditions like COVID-19. It helps guide treatment decisions, such as oxygen therapy or adjustments to medications.

Short name

Arterial Oxygen Saturation (SaO₂)

Frequently asked questions

What causes low arterial oxygen saturation?
Low SaO₂ can result from poor lung function (e.g., from asthma, emphysema, or pneumonia), high altitude, heart problems that reduce blood flow, or conditions like sleep apnea that disrupt breathing during sleep.
How is low arterial oxygen saturation treated?
Treatment depends on the cause. For example, breathing treatments, oxygen therapy, or managing underlying conditions like heart failure may be recommended. Your doctor will tailor treatment to your specific needs.
Can I get this test at home?
Yes, some healthcare providers offer at-home pulse oximetry devices, which measure oxygen saturation in your fingertip. However, these devices are not as precise as lab tests and should not replace professional medical evaluation.
  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