B-cell Lymphocyte Count (Absolute)
This test measures the number of B cells, a type of white blood cell important for producing antibodies that help fight infections.
["B-cell counts help assess immune function and identify conditions like low immunity or immune-related diseases."]
Key facts at a glance
- LOINC
- 26566-0
- Short code
- CD19LAM
- Synonyms
- CD19+Lambda+ Cells NFr Spec
- Category
- chemistry
- Sample
- serum
- Container
- Heparinized (sodium heparin or lithium heparin) sterile tube for flow cytometry; EDTA tubes acceptable for some platforms; specific B-cell subset panels often require ACD (acid citrate dextrose) or heparin anticoagulant
- Units
- N/A
- Ref low
- 40
- Ref high
- 65
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- Flow cytometry using fluorescently labeled monoclonal antibodies against CD19 (pan-B-cell marker) and surface immunoglobulin light chains (kappa and lambda) to enumerate B-lymphocyte subsets expressing lambda light chains
- CPT
- 86356 (Flow cytometry, cell surface, cytoplasmic, or nuclear marker, technical component only); 86355 (B-cell marker panel) - verify with current CPT manual
- SNOMED
- 440622008 (Measurement of B lymphocyte subset); 116646005 (CD19 antigen) - combined for full procedure coding
- Specimen volume
- Minimum 3-5 mL whole blood for adult panels; 1-2 mL adequate for pediatric samples; bone marrow aspirate 1-2 mL when applicable
- Stability
- Specimen must be processed within 24-30 hours of collection when stored at room temperature (18-25°C); refrigerated storage (2-8°C) may extend viability to 48 hours but is not preferred for lymphocyte subset analysis; do not freeze whole blood for flow cytometry
- Hemolysis max
- 100
- Lipemia max
- 200
- Icterus max
- 50
- TAT
- 4–48 hours
- Order
- routine
Why This Test Matters
B cells are a key part of your immune system. They produce antibodies that help your body fight off bacteria and viruses. Low or high B-cell counts can signal problems like infections, autoimmune diseases, or certain cancers.
What to Expect Before the Test
No special preparation is needed. You may have a blood draw from a vein in your arm, similar to other blood tests. You might feel a slight pinch, but it usually doesn’t cause discomfort.
What the Results Mean
Results are typically reported as a count of B cells per microliter of blood. While reference ranges vary by lab, doctors use these numbers to compare with your overall health and symptoms.
Common Reasons for Testing
Doctors may order this test to check for immune disorders, infections, or conditions like chronic lymphocytic leukemia (CLL), HIV, or other immune-related diseases.
Reference range
CD19+ Lambda+ B-cells typically represent 5-10% of total lymphocytes and 40-65% of total CD19+ B-cells (kappa:lambda ratio reference 0.8-2.5). Absolute counts vary by age; results should be interpreted alongside total CD19+ count and kappa:lambda ratio.N/A
No fasting required. Avoid recent (within 24 hours) corticosteroid or immunosuppressive therapy administration if clinically feasible, as these can transiently alter lymphocyte subset distributions. Patient should be well-hydrated. Inform laboratory of any recent vaccinations, transfusion history, or active infections.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
A low B-cell count may indicate weakened immunity, while an elevated count could suggest conditions like multiple myeloma, certain infections, or autoimmune disorders. Your doctor will interpret results in the context of your health history and symptoms.
Short name
B-Cell Count
Frequently asked questions
How long does it take to get my results?
Can I eat or drink before this test?
Is there any risk or discomfort with this test?
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 15, 2026. · Read our editorial policy