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Oxygen saturation of hemoglobin in whole blood

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

This test measures how much oxygen is bound to hemoglobin in your red blood cells, providing a snapshot of your oxygen levels in the blood.

Quick summary

["Helps assess lung function and oxygen delivery to tissues."]

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

Key facts at a glance

LOINC
2714-4
Short code
OxyHgb MFr BldA
Synonyms
OxyHgb MFr BldA
Category
hematology
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Ref low
12
Ref high
17.5
Critical range
7 N/A – 20 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
85018
SNOMED
900000000000003004
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 Does This Test Measure?

Oxygen saturation (SpO₂) reflects the percentage of hemoglobin molecules carrying oxygen in your blood. A lower value may indicate poor oxygen exchange, often due to conditions like lung disease or anemia.

Why Is This Test Done?

Doctors may order this test to evaluate breathing problems, monitor chronic conditions like heart or lung disease, or check for complications during anesthesia or surgery.

Common Conditions Monitored

Conditions such as chronic obstructive pulmonary disease (COPD), pneumonia, heart failure, or anemia can affect oxygen levels. It’s also used during sleep studies or in emergency settings for quick assessment.

How Is the Test Performed?

A small sensor is placed on your finger or ear lobe to measure oxygen saturation via a pulse oximeter. No blood draw is needed, and it’s painless.

Reference range

Adult males: 13.5-17.5 g/dL; Females: 12.0-16.0 g/dLN/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

SpO₂ (Oxygen Saturation)

Frequently asked questions

What Are Normal Results?
Normal results typically range between 95% and 100% for healthy individuals at rest. Values below 90% may warrant further medical attention.
Can I Eat or Drink Before the Test?
No special preparation is needed. You can eat, drink, or take medications as usual, as this test is quick and non-invasive.
How Long Does It Take to Get Results?
Results are usually available immediately after the sensor is removed, often within minutes.
  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