B-cell Lymphocyte Count (Absolute)
This test measures the number of B cells, a type of white blood cell important for making antibodies that help fight infections and diseases like cancer.
["B cells help your immune system defend against harmful substances."]
Key facts at a glance
- LOINC
- 17123-1
- Short code
- CD19LAM
- Synonyms
- CD19+Lambda+ Cells NFr Bld
- Category
- chemistry
- Sample
- whole-blood
- Container
- EDTA (lavender/purple-top) anticoagulant tube for flow cytometry; sodium heparin (green-top) tube also acceptable
- Units
- N/A
- Ref low
- 0.7
- Ref high
- 2.1
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- Flow cytometry using fluorescently labeled monoclonal antibodies against CD19 (B-cell marker) and surface immunoglobulin lambda light chain
- CPT
- 86356
- SNOMED
- 395146008
- Specimen volume
- 3-5 mL of whole blood for adults; minimum 1 mL for pediatric patients
- Stability
- Specimen must be processed within 24-48 hours of collection when stored at room temperature (20-25°C); do not refrigerate. Maintain at ambient temperature and analyze as soon as possible to preserve cell viability and surface marker integrity.
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 24–72 hours
- Order
- routine
Why Is This Test Done?
Your doctor may order a B-cell count to check for immune system issues, such as infections, autoimmune diseases, or conditions like leukemia or lymphoma. It can also help monitor treatment responses in certain blood disorders.
What Does a Low or High Count Mean?
A low B-cell count might indicate immune suppression, certain cancers, or long-term immune disorders. A high count could suggest overactive immune responses or conditions like chronic infections.
Sample Collection and Preparation
This test uses a sample of whole blood drawn from a vein. The blood is processed to separate the B cells from other blood components for accurate counting.
When Might You Get Results Back?
Results are typically available within 1–3 business days, depending on lab processing times. Your doctor will discuss the results with you during your follow-up visit.
Reference range
Results reported as percentage and absolute count of CD19+ B cells expressing lambda light chain relative to total B cells; lambda:kappa ratio is the primary clinical interpretation (normal lambda:kappa ratio approximately 0.7-2.1). Reference values vary by laboratory.N/A
No special patient preparation required. Recent corticosteroid therapy, chemotherapy, or immunotherapy may affect results. Inform laboratory of recent vaccinations, blood transfusions, or immunosuppressive medications.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance: B-Cell Counts in Health and Disease
Short name
B-cell count
Frequently asked questions
What Are Common Causes of Abnormal Results?
How Often Should This Test Be Done?
Can Diet or Lifestyle Affect B-Cell Counts?
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