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Oxygen Saturation in Whole Blood by Pulse Oximetry

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

This test measures how much oxygen is bound to your red blood cells while you're breathing normally. It’s a quick, non-invasive way to check your blood oxygen levels.

Quick summary

["Pulse oximetry provides a snapshot of your oxygen levels, often used to monitor breathing or detect potential issues like low oxygen in the blood."]

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

Key facts at a glance

LOINC
59408-5
Short code
SaO2 % BldA PulseOx
Synonyms
SaO2 % BldA PulseOx
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
pulse-oximetry
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

How It Works

A small sensor is placed on your finger, toe, or ear. It shines light through your blood vessels and measures the amount of oxygen attached to hemoglobin, the protein that carries oxygen in your blood.

What It Measures

The test gives you a percentage (SpO₂) representing the saturation of hemoglobin with oxygen. Normal values typically range between 95% and 100%, but this can vary based on health status and altitude.

Common Uses

Doctors use pulse oximetry to monitor patients during procedures, check for breathing problems, assess sleep apnea, or evaluate symptoms like shortness of breath or fatigue.

Limitations and Considerations

While pulse oximetry is generally safe and painless, it may not always give accurate readings in certain conditions, such as cold hands, dark skin tones, or severe anemia. It does not measure the actual oxygen content in your blood but rather the saturation level.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Low oxygen saturation (SpO₂ below 90%) can indicate serious conditions like severe lung disease, heart problems, or respiratory infections. High readings (above 100%) are rare but may occur in extreme cases or with certain medications. Always discuss results with your healthcare provider for personalized interpretation.

Short name

SpO₂ (Pulse Oximetry)

Frequently asked questions

Why might I need this test?
Your doctor may order this test to monitor your breathing, check for sleep apnea, evaluate symptoms like dizziness or fatigue, or assess your response to treatment for conditions like heart disease or lung disorders.
What does a low or high oxygen saturation mean?
A low oxygen saturation (below 90%) may suggest breathing difficulties, poor circulation, or other health issues. A high saturation (above 100%) is unusual and could be due to factors like high altitude or certain medications. Your doctor will interpret results in the context of your overall health.
Can this test be done at home?
Yes, some people use at-home pulse oximeters to monitor their oxygen levels, especially those with chronic conditions like COPD or heart disease. However, results should be reviewed by a healthcare provider for accurate diagnosis and management.
  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