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B-cell Lymphocyte Count (Absolute)

Published: August 9, 2026Updated: August 15, 2026

This test measures the number of B-cells (a type of white blood cell) in your blood to help assess immune function, particularly in conditions involving immune disorders or cancer.

Quick summary

["B-cell counts help diagnose and monitor immune-related conditions and cancers like lymphoma."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 15, 2026Editorial policy

Key facts at a glance

LOINC
27893-7
Short code
CD19CD23
Synonyms
CD19+CD23+ Cells NFr Bld
Category
chemistry
Sample
whole-blood
Container
EDTA (purple-top) vacutainer tube; ACD (yellow-top) tube is also acceptable for flow cytometry immunophenotyping
Units
N/A
Ref low
5
Ref high
15
Fasting
false
Population
adult
Sex
all
Age range
0–120 years
Method
Flow cytometry using fluorescently labeled monoclonal antibodies against CD19 and CD23 surface markers, with identification and enumeration performed on a flow cytometer
CPT
86356 (Flow cytometry, cell surface, cytoplasmic, or nuclear marker, technical component only; each marker); additional markers billed separately
SNOMED
269900004 (Lymphocyte subset analysis); 313054001 (B-lymphocyte count)
Specimen volume
3-5 mL of whole blood for adults; minimum 1 mL for pediatric patients
Stability
Specimen should be processed within 24-30 hours of collection when stored at room temperature (18-25°C). Do not refrigerate. Optimal analysis time is within 6-8 hours of collection for best viability and accurate subset enumeration.
Hemolysis max
100
Lipemia max
300
Icterus max
50
TAT
4–24 hours
Order
routine

Why This Test Is Done

Your healthcare provider may order this test if you have symptoms like frequent infections, autoimmune diseases (such as lupus or rheumatoid arthritis), or if you’re being evaluated for or treated for conditions like leukemia, lymphoma, or other blood disorders. It may also be used to monitor immune responses during chemotherapy or other treatments.

Sample Collection and Preparation

A small sample of your blood is drawn from a vein, usually in your arm. The blood is sent to a lab where it is analyzed to count the B-cells. No special preparation is needed, but fasting may be required depending on other tests ordered together.

What to Expect Before or After the Test

You may experience mild discomfort or bruising at the injection site, but this usually fades quickly. If you’re on blood-thinning medication, inform your provider before the test. There are no restrictions on diet or activity unless combined with other tests.

Normal vs. Abnormal Results

Results are interpreted by your healthcare provider based on your overall health and medical history. Low B-cell counts may suggest immune suppression or certain cancers, while very high counts could indicate overactive immune responses or other conditions.

Reference range

CD19+ B-lymphocytes typically constitute 5-15% of total lymphocytes; CD19+CD23+ subset represents a variable proportion of total B-cells. Reference ranges are laboratory-specific and should be interpreted alongside complete lymphocyte subset panel.N/A

Specimen: whole-blood

No fasting required. Avoid strenuous exercise prior to specimen collection. Patients should be well-hydrated. Inform the laboratory of any recent corticosteroid, immunosuppressive therapy, or chemotherapy, as these may affect lymphocyte subset counts.

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 impaired immune system, which can make you more susceptible to infections. It could also be linked to conditions like autoimmune diseases, certain cancers, or treatments that suppress the immune system, such as chemotherapy.
What does a high B-cell count mean?
High B-cell counts might suggest overactive immune responses, such as in certain autoimmune conditions or chronic infections. In some cases, it could also be associated with conditions like chronic lymphocytic leukemia or other hematologic disorders.
How often should I get this test?
Your provider will determine how often you need this test based on your medical condition, treatment plan, and symptoms. Regular monitoring may be required if you’re undergoing treatment for a blood disorder or cancer.
  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 15, 2026. · Read our editorial policy