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Oxygen Saturation in Whole Blood (Pulse Oximetry Measurement)

Published: August 9, 2026Updated: August 17, 2026

This test measures how much oxygen is bound to hemoglobin in your red blood cells, expressed as a percentage. It’s commonly used to assess oxygen levels in the bloodstream.

Quick summary

["Oxygen saturation reflects how well your blood delivers oxygen to your body’s tissues."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC
2713-6
Short code
SaO2 % Bld from pO2
Synonyms
SaO2 % Bld 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) is determined by analyzing whole blood, often via a fingerstick or pulse oximeter device. The test quantifies the proportion of hemoglobin molecules carrying oxygen, typically reported as a percentage (e.g., 95% saturation).

Why It’s Done

Doctors may order this test to evaluate lung function, detect conditions like anemia, heart disease, or respiratory disorders, or monitor chronic illnesses such as COPD or sleep apnea.

Common Uses

Results are used to diagnose or monitor conditions affecting oxygen transport, such as severe infections, blood disorders, or circulatory issues. It’s also critical in emergency settings for quick assessment.

What to Expect

You’ll likely have a small blood sample drawn from your finger or use a portable device at home. The process is quick and painless, though you may feel a slight pinch.

Reference range

NCBI: PaO2 80-100 mmHgN/A

Specimen: whole-blood

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.

◆Associated findings1

Short name

O₂ Saturation from Blood

Frequently asked questions

How often should I get this test?
Frequency depends on your health condition. Healthy adults may not need routine testing unless advised by a doctor. Chronic conditions like COPD or diabetes might require regular monitoring.
What does a normal range mean?
A normal range isn’t always fixed—it varies by age, health, and activity level. A saturation of 95%–100% is typical for healthy adults at rest, but your provider will interpret results based on your specific situation.
Can I do anything to prepare?
No special preparation is needed. Avoid caffeine or heavy meals 30 minutes before testing if using a fingerstick sample, as they might affect accuracy.
  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 17, 2026. · Read our editorial policy