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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, which helps your doctor check for infections, inflammation, or other health conditions.

Quick summary

["White blood cells protect your body from infections and illness."]

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

Key facts at a glance

LOINC
813-6
Short code
WBC # Snv Auto
Synonyms
WBC # Snv Auto
Category
chemistry
Sample
fluid
Container
Sterile tube
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
2-5 mL
Stability
Room temperature: 2h, Refrigerated: 24h
Hemolysis max
300
TAT
4–24 hours
Order
routine

Why This Test Is Done

Doctors order a white blood cell count to diagnose or monitor conditions such as infections (like colds, flu, or bacterial infections), immune system disorders, or blood disorders. It may also be used during pregnancy to check for infections or before certain treatments.

What to Expect Before the Test

No special preparation is needed. You may have a small needle inserted into your arm or hand to draw blood. If you’re nervous, let your doctor or phlebotomist know—they can help make it more comfortable.

What the Test Results Mean

Results show your total white blood cell count, but they don’t identify which types of white blood cells are present. High counts may signal infection or inflammation, while low counts could indicate immune issues or blood disorders. Always discuss results with your doctor.

Common Conditions Monitored

This test is often checked alongside other blood tests to assess overall health, especially if you have symptoms like fever, fatigue, or unexplained weight loss.

Reference range

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

Specimen: fluid

No special preparation required. Stay well hydrated.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

White blood cells play a critical role in fighting infections and detecting diseases. Abnormal counts can signal underlying health concerns that require further evaluation, such as chronic illnesses or immune deficiencies.

Short name

WBC Count

Frequently asked questions

What causes a high white blood cell count?
High white blood cell counts can result from infections (like pneumonia or urinary tract infections), stress, inflammation, or certain medications. It may also appear in some cancers or autoimmune diseases.
What causes a low white blood cell count?
Low white blood cell counts can be due to infections, certain medications, chemotherapy, or immune system disorders. Chronic conditions like HIV or long-term stress may also lower them.
Is there anything I should avoid before this test?
No restrictions apply, but inform your doctor if you’re on blood-thinning medications or have a history of bleeding disorders.
  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