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White Blood Cell Count (Automated)

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

This test measures the number of white blood cells in your blood. White blood cells help your body fight infections and protect against illness.

Quick summary

["Your WBC count helps doctors check for infections, inflammation, or other health issues."]

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

Key facts at a glance

LOINC
811-0
Short code
WBC # Smn Auto
Synonyms
WBC # Smn Auto
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
4.5
Ref high
11
Critical range
2 N/A – 30 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
automated-count
CPT
85004
SNOMED
900000000000003002
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 Does This Test Measure?

White blood cells (WBCs) are part of your immune system. They help your body fight off bacteria, viruses, and other invaders. This test counts the total number of WBCs in a sample of your blood. Different types of WBCs (like neutrophils, lymphocytes, etc.) can also be analyzed separately, but this test focuses on the total count.

Why Might You Need This Test?

Doctors order this test to diagnose or monitor conditions such as infections (like pneumonia or urinary tract infections), certain cancers (like leukemia), autoimmune diseases, or to check if your immune system is working properly after treatments like chemotherapy.

What to Expect Before the Test

You won’t need any special preparation for this test. A healthcare provider will take a small blood sample from a vein in your arm. It usually takes a few minutes, and you may feel a slight pinch when the needle is inserted. You can eat and drink normally before the test.

What Happens During the Test?

The blood sample is sent to a lab where it is analyzed automatically using a machine. The machine counts the number of white blood cells in your blood. Results are usually available within a few hours or the next day.

Reference range

Adult: 4.5-11.0 x 10^9/LN/A

Specimen: serum

No special preparation required. Stay well hydrated.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

WBC Count

Frequently asked questions

What Are Normal Results?
There is no single set of normal results for WBC count because it can vary based on age, health status, and other factors. Your doctor will compare your results to your baseline or expected range for your specific situation.
Can I Eat or Drink Before the Test?
Yes, you can eat and drink normally before this test. No special preparation is needed.
How Long Will It Take to Get the Results?
Results are typically available within a few hours to a couple of days, depending on your lab’s processing time.
  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