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B-cell Lymphocyte Count (Absolute)

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

This test measures the number of B-cells (a type of white blood cell) in your blood to help assess immune function, monitor conditions like chronic lymphocytic leukemia, or evaluate immune responses.

Quick summary

["B-cell counts help doctors track immune health and certain blood disorders."]

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

Key facts at a glance

LOINC
51337-4
Short code
CD19CD43
Synonyms
CD19+CD43+ Cells NFr Bld
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA) or sodium heparin tube for flow cytometry; ACD-A tube is also acceptable. Collect in a sterile vacuum tube appropriate for hematology/immunology studies.
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
Flow cytometry using fluorescently-labeled monoclonal antibodies against CD19 and CD43 surface markers, with subsequent analysis on a flow cytometer
CPT
86355
SNOMED
399014001
Specimen volume
3-5 mL of whole blood for adults; minimum 1 mL for pediatric patients. For flow cytometry, cell count adequacy should be verified by the performing laboratory.
Stability
Specimen should be processed within 24 hours at room temperature (18-25°C) for optimal results. Refrigeration (2-8°C) may extend stability to 48 hours but may affect viability. Do not freeze.
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
24–72 hours
Order
routine

Why This Test Is Done

Your doctor may order this test if you have symptoms of an immune disorder, such as frequent infections, fatigue, or unexplained weight loss. It’s also used to monitor conditions like chronic lymphocytic leukemia (CLL), autoimmune diseases, or after treatments like chemotherapy. Sometimes, it’s part of a routine checkup for people at higher risk of certain blood 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) to draw blood. It usually takes a few minutes, and you may feel a brief pinch. If you’re nervous, let your healthcare provider know—they can help make it more comfortable.

What the Test Results Mean

Results show the number of B-cells in your blood. Low counts may suggest immune deficiencies, infections, or certain cancers. High counts could indicate conditions like CLL, autoimmune diseases, or overactive immune responses. Your doctor will interpret results in the context of your overall health and symptoms.

Common Conditions Monitored

This test is often used to diagnose or monitor conditions like chronic lymphocytic leukemia, autoimmune diseases (e.g., rheumatoid arthritis), or immune system disorders. It may also help evaluate responses to treatments for blood cancers or immune-related illnesses.

Reference range

Reference ranges vary by laboratory; typically expressed as a percentage of total lymphocytes or as absolute count (cells/μL). CD19+CD43+ cells normally represent a small subset of B lymphocytes in peripheral blood. Please refer to individual laboratory reference values.N/A

Specimen: whole-blood

No special patient preparation required. Samples should ideally be processed within 24 hours of collection for optimal viability. Avoid exercise immediately prior to venipuncture as it may transiently alter lymphocyte distribution.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

B-cell count

Frequently asked questions

What does a low B-cell count mean?
A low B-cell count may indicate an immune deficiency, chronic infection, or certain blood cancers. It could also be due to treatments like chemotherapy or autoimmune diseases. Your doctor will review your symptoms and other test results to determine the cause and next steps.
How often should I get this test?
Frequency depends on your health condition and treatment plan. If you have a chronic illness like CLL, your doctor may recommend regular monitoring. Otherwise, this test is usually done only when needed for diagnosis or follow-up. Always follow your healthcare provider’s instructions.
Can lifestyle changes affect B-cell counts?
While diet and exercise generally support immune health, they don’t directly change B-cell counts. However, managing stress, avoiding smoking, and staying hydrated can help overall health, which may indirectly support immune function. Your doctor will focus on medical factors when interpreting results.
  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