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White Blood Cell Count (with Differential Analysis)

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

This test measures the types and proportions of white blood cells in your blood, helping doctors assess immune function, infection risk, or inflammatory conditions.

Quick summary

["Understanding your blood’s immune cell balance can help identify health concerns early."]

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

Key facts at a glance

LOINC
15112-6
Short code
LAP WBC-aCnc
Synonyms
LAP WBC-aCnc
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
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

Why This Test Is Done

Doctors may order a white blood cell differential when you have symptoms like fever, fatigue, or unexplained weight loss. It’s also used to monitor conditions like infections, autoimmune diseases, or blood disorders. Sometimes, it’s part of routine check-ups or before treatments that affect the immune system.

What to Expect Before the Test

No special preparation is needed. You’ll have a small needle inserted into your arm or hand to draw blood. The process takes a few minutes, and you may feel a brief pinch. If you’re nervous, let your healthcare provider know—they can offer tips to stay calm.

What the Results Mean

The differential breaks down white blood cells into categories like neutrophils, lymphocytes, eosinophils, basophils, and monocytes. Each type serves a purpose: for example, high neutrophils might suggest infection, while high lymphocytes could indicate immune activity. Your results will be compared to standard ranges for your age and health.

Common Conditions Linked to Abnormal Results

Low or high counts of certain white blood cells can signal problems like infections, allergies, or chronic illnesses. For instance, a low lymphocyte count might raise concerns about weakened immunity, while elevated eosinophils could hint at parasitic infections or asthma. Always discuss your results with your doctor.

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 Differential

Frequently asked questions

What does a ‘differential’ test tell me about my blood?
A differential test shows the types and proportions of white blood cells in your blood. It helps identify which cells are elevated or low, which can indicate infections, immune responses, or other health issues. For example, high neutrophils often mean a bacterial infection, while high lymphocytes might suggest a viral infection or immune activation.
How often should I get this test?
Your doctor will decide how often to check your white blood cell differential based on your symptoms, medical history, and treatment plan. Some people get it once a year as part of routine care, while others may need it more frequently if they have conditions like cancer, autoimmune diseases, or frequent infections.
Can diet or lifestyle affect my white blood cell counts?
Yes, diet and stress can influence white blood cell levels. For example, poor nutrition may weaken your immune system, while chronic stress can temporarily alter cell counts. Avoiding extreme stress, eating a balanced diet, and staying hydrated may support healthier blood cell function. Always follow your doctor’s advice for any changes.
  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