Cell count in whole blood (with differential analysis)
This test measures the total number of white blood cells and breaks them down into their types (neutrophils, lymphocytes, monocytes, eosinophils, and basophils) in your blood sample.
["Understanding your immune system’s cell composition helps diagnose infections, inflammation, or blood disorders."]
Key facts at a glance
- LOINC
- 26556-1
- Short code
- CD103
- Synonyms
- CD103 Cells NFr Spec
- Category
- chemistry
- Sample
- serum
- Container
- Heparinized tube (sodium heparin or lithium heparin) for flow cytometry; EDTA tube may be acceptable for some specimen types
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- Flow cytometry
- CPT
- 86355
- SNOMED
- 49640000
- Specimen volume
- 3-5 mL whole blood; minimum 1 mL for pediatric or limited samples
- Stability
- Specimen should be processed within 24-48 hours of collection when stored at room temperature (20-25°C); do not refrigerate as this may affect cell viability and surface marker expression
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 24–72 hours
- Order
- routine
What Does a Differential Count Measure?
A differential count identifies the proportion of each type of white blood cell in your blood. For example, high neutrophils might suggest infection, while high lymphocytes could indicate chronic conditions like lupus. This helps pinpoint whether your immune system is responding normally or unusually.
How Is This Test Performed?
A small blood sample is drawn from your arm and sent to the lab. Microscopic analysis then counts and categorizes each white blood cell type, providing a detailed breakdown of your immune cell makeup.
When Might You Need This Test?
Doctors order a differential count to investigate symptoms like frequent infections, unexplained fevers, or signs of immune system dysfunction. It’s also used before treatments that affect the immune system, such as chemotherapy or certain medications.
What Are Common Findings?
Abnormal results may reveal conditions like leukemia (high white cells), severe infections (elevated neutrophils), or immune deficiencies (low lymphocytes). Always discuss any deviations with your healthcare provider.
Reference range
Reference range varies by laboratory; CD103 expression is typically reported as percentage of lymphocytes or cells positive for CD103. Generally, CD103+ cells constitute a small subset of lymphocytes in peripheral blood.N/A
No special patient preparation required. Specimen should be collected and processed according to flow cytometry requirements to maintain cell viability.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
Blood Cell Count with Differential
Frequently asked questions
Why do I need this test if I’m feeling healthy?
Can diet affect my blood cell counts?
How long does it take to get results?
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