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B-cell Lymphocyte Count (Absolute Count)

Published: August 9, 2026Updated: August 16, 2026

This test measures the number of B-cells, a type of white blood cell important for immune function, in your blood.

Quick summary

["Knowing your B-cell count helps assess immune health and response to treatments."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
57394-9
Short code
CD19CD34
Synonyms
CD19+CD34+ Cells NFr Fld
Category
chemistry
Sample
serum
Container
Sterile, anticoagulant-treated collection tube appropriate for the body fluid type (e.g., EDTA tube for peripheral blood; sterile container or heparinized tube for CSF, pleural, peritoneal, or other body fluids)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
0–99 years
Method
Flow cytometry using fluorescently labeled antibodies against CD19 and CD34 surface markers, with viability staining (e.g., 7-AAD) and enumeration of cells in body fluid specimens
CPT
86355
SNOMED
428570000
Specimen volume
Minimum 1 mL of body fluid; larger volumes (3-5 mL) preferred when available to ensure adequate cell yield for analysis
Stability
Specimens should be processed within 24 hours of collection when stored at room temperature (18-25°C). If processing is delayed, store at 2-8°C and analyze within 48 hours. Viability may decline with prolonged storage.
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–48 hours
Order
routine

Why This Test Matters

B-cells are a key part of your immune system, helping your body fight infections and produce antibodies. This test helps doctors check if your B-cell levels are within a healthy range, especially important for people with immune disorders, those undergoing cancer treatment, or those with conditions like lupus or rheumatoid arthritis.

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 tube. The process usually takes a few minutes, and you may feel a brief pinch. If you’re nervous, let your healthcare provider know.

What the Results Mean

Results show the absolute number of B-cells per microliter (µL) of blood. Low levels may suggest immune deficiencies, autoimmune diseases, or certain cancers. High levels could indicate overactive immune responses or other conditions. Your doctor will interpret results in the context of your overall health.

Common Reasons for Testing

Doctors may order this test if you have symptoms like frequent infections, fatigue, or unexplained swelling. It’s also used to monitor treatments for conditions like leukemia, lymphoma, or immune disorders.

Reference range

Reference ranges are highly dependent on specimen type, clinical context, and laboratory methodology. CD19+/CD34+ co-expression is typically rare in peripheral blood; results should be interpreted in conjunction with clinical findings and concurrent flow cytometry panels.N/A

Specimen: serum

No special patient preparation required. Specimen collection should follow standard aseptic technique appropriate to the body fluid sampled. Avoid contamination with peripheral blood when possible.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

B-Cell Count

Frequently asked questions

What causes low B-cell counts?
Low B-cell counts can result from immune system disorders (e.g., HIV/AIDS, lupus), certain cancers (e.g., non-Hodgkin lymphoma), or treatments like chemotherapy or radiation. Chronic infections or autoimmune diseases may also reduce B-cell numbers.
What causes high B-cell counts?
High B-cell counts can occur in conditions like chronic infections, certain autoimmune diseases (e.g., rheumatoid arthritis), or as a side effect of medications. Rarely, it may indicate a blood disorder like chronic lymphocytic leukemia.
How often should I get this test?
Frequency depends on your health condition. If you’re undergoing treatment for a blood disorder or immune-related illness, your doctor may recommend regular monitoring. Otherwise, this test is usually done only when needed for diagnosis or management.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

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.

Medical Disclaimer

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