B-cell Lymphocyte Count (Peripheral Blood)
This test measures the number of B cells, a type of white blood cell important for immune function, in your blood.
["B cells help your body fight infections and produce antibodies."]
Key facts at a glance
- LOINC
- 103681-3
- Short code
- CD19
- Synonyms
- CD19 Cells/lymph NFr Bld
- Category
- chemistry
- Sample
- whole-blood
- Container
- EDTA (purple-top) tube or ACD (yellow-top) tube for flow cytometry
- Units
- N/A
- Ref low
- 5
- Ref high
- 15
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- ≥ 0 years
- Method
- Flow Cytometry
- CPT
- 86356
- SNOMED
- 416928007
- Specimen volume
- 3-5 mL whole blood (adult); minimum 1 mL (pediatric)
- Stability
- Room temperature: 24-48 hours; refrigerated (2-8°C): up to 48 hours; do not freeze. Process within 24 hours for optimal viability.
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 4–24 hours
- Order
- routine
Why This Test Might Be Ordered
Your healthcare provider may recommend this test if you have symptoms like frequent infections, fatigue, or swelling in your lymph nodes. It could also be part of an evaluation for autoimmune diseases, certain cancers (like lymphoma), or immune system disorders.
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.
What the Test Results Mean
Results show the count of B cells in your blood. Low levels may indicate immune deficiencies or certain diseases, while high levels could suggest overactive immune responses or conditions like chronic infections.
Common Conditions Linked to B-Cell Counts
Abnormal B-cell counts can signal conditions like chronic lymphocytic leukemia, autoimmune diseases (e.g., lupus), or infections (e.g., HIV). Your provider will discuss findings in the context of your full health picture.
Reference range
CD19+ B lymphocytes typically comprise 5-15% of total lymphocytes in healthy adults; absolute counts vary by age with higher values in childrenN/A
No fasting required. Patient should be well-hydrated. Avoid recent immunizations or immunosuppressive therapy when possible. Inform laboratory of any recent blood transfusions.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance
Short name
B-Cell Count
Frequently asked questions
How often will I need this test?
Can I eat or drink before the blood draw?
What if my B-cell count is outside the normal range?
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