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White Blood Cell Count with Differential (Blood)

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

This test measures the types and proportions of white blood cells in your blood, helping identify infections, immune responses, or other conditions affecting your blood cells.

Quick summary

["Understanding your white blood cell types can help diagnose health issues early."]

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

Key facts at a glance

LOINC
33028-2
Short code
WBC # Bld BPU
Synonyms
WBC # Bld BPU
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
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
CPT
85004
SNOMED
900000000000003002
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

A white blood cell differential (or WBC differential) breaks down the total white blood cell count into specific types: neutrophils, lymphocytes, monocytes, eosinophils, and basophils. Each type plays a distinct role in your immune system. The test helps determine if certain cell types are elevated or low, which can signal different health concerns.

Why It’s Done

Doctors may order a WBC differential to diagnose infections (like bacterial or viral), autoimmune diseases, blood disorders, or to monitor treatment effectiveness. It’s often part of a complete blood count (CBC) but provides deeper insight into immune function.

Common Reasons for Testing

Common reasons include unexplained fevers, frequent infections, fatigue, or symptoms like swollen lymph nodes. It may also be used before surgery, during chemotherapy, or to check for conditions like leukemia or anemia.

What to Expect Before the Test

No special preparation is needed. You’ll have a small needle inserted into a vein (usually in your arm), and blood will be drawn into a test tube. The process takes about 5 minutes, and you may feel a brief pinch.

Reference range

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

Specimen: whole-blood

No special preparation required. Stay well hydrated.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

WBC Differential

Frequently asked questions

How elevated or low levels of specific white blood cells can indicate health issues.
For example, a high neutrophil count might suggest bacterial infection, while a high lymphocyte count could indicate viral infection or chronic disease. Low eosinophils might point to allergies or parasitic infections, and low basophils could signal immune disorders.
FAQ 1
This test is typically done as part of a routine blood test and doesn’t require fasting. Results are usually ready within 24 hours, depending on lab processing.
FAQ 2
Yes, certain medications (like steroids) or recent illness can affect white blood cell counts. Always inform your doctor about all medications or supplements you’re taking.
  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