White Blood Cell Differential Count (Serum/Plasma or Whole Blood Leukocyte Profile)
This test measures the types and proportions of white blood cells in your blood, helping identify infections, immune responses, or other health conditions.
["Understanding your immune system’s cell balance can reveal hidden issues like infections or immune disorders."]
Key facts at a glance
- LOINC
- 108340-1
- Short code
- LAP Msmt WBC
- Synonyms
- LAP Msmt WBC
- 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 Matters
White blood cells (WBCs) are your body’s defense force, fighting infections and keeping you healthy. This test breaks down the different types of WBCs—such as neutrophils, lymphocytes, monocytes, eosinophils, and basophils—to check for imbalances that might signal problems like chronic infections, allergies, or blood disorders.
What to Expect Before the Test
No special preparation is needed, but you may have a small needle inserted into your arm for a blood draw. If you’re taking certain medications (like steroids), let your provider know, as they can affect your WBC counts.
Common Reasons for This Test
Doctors order this test to diagnose or monitor conditions like infections (e.g., pneumonia, sinusitis), autoimmune diseases (e.g., lupus), blood cancers (e.g., leukemia), or allergic reactions. It may also be used to check for signs of inflammation or to guide treatment decisions.
What the Results Mean
Results show the percentage of each WBC type. For example, a high neutrophil count might indicate infection, while a low lymphocyte count could signal immune suppression. Your provider will interpret these results in the context of your overall health.
Reference range
Adult: 4.5-11.0 x 10^9/LN/A
No special preparation required. Stay well hydrated.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Abnormal WBC differentials can signal underlying health issues, such as chronic infections (e.g., tuberculosis), inflammatory diseases (e.g., rheumatoid arthritis), or immune deficiencies. It’s also useful for tracking how well treatments are working or detecting early signs of blood disorders.
Short name
WBC Differential
Frequently asked questions
How often should I get this test?
What are the typical reference ranges?
Can diet or lifestyle affect my WBC count?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
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.
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