Skip to content

B-cell Lymphocyte Count (Absolute Number)

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

This test measures the number of B cells in your blood, which are a type of white blood cell involved in immune response.

Quick summary

["B-cell counts help assess immune function and identify potential immune disorders."]

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

Key facts at a glance

LOINC
57433-5
Short code
CD19LAMBF
Synonyms
CD19+Lambda+ Cells NFr Fld
Category
chemistry
Sample
serum
Container
Sterile body fluid collection container (e.g., sterile conical tube); EDTA or heparin tube acceptable for flow cytometry preservation depending on laboratory protocol
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 lambda light chain markers, with enumeration by multi-parameter analysis on a flow cytometer
CPT
86356
SNOMED
428070006
Specimen volume
Minimum 1-5 mL of body fluid; larger volumes preferred when feasible to ensure adequate cell yield for analysis
Stability
Specimen should be processed within 4-6 hours of collection at room temperature (18-25°C); refrigerated storage (2-8°C) may extend stability to 24 hours per laboratory-specific validation
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
24–72 hours
Order
routine

Why Is This Test Done?

Your healthcare provider may order this test to evaluate your immune system, diagnose conditions like chronic infections, autoimmune diseases, or certain cancers (e.g., lymphoma). It can also help monitor treatment progress for blood disorders or immune-related illnesses.

What to Expect Before the Test

No special preparation is usually needed. You may have a small needle inserted into a vein (typically in your arm) to draw blood. If you’re on blood-thinning medication, let your provider know beforehand.

What the Results Mean

Results are compared to your baseline or lab reference ranges (if applicable). Low counts may indicate immune suppression, high counts could suggest overactive immune responses or certain infections.

Common Conditions Monitored

This test is often used to monitor conditions like leukemia, HIV/AIDS, or after chemotherapy/radiation for immune recovery. It may also help diagnose or track autoimmune diseases like lupus or rheumatoid arthritis.

Reference range

Reference ranges are laboratory-specific and vary based on cell population, fluid type, and clinical context. Typically reported as absolute count (cells/μL) or percentage of total lymphocytes. Consult laboratory-specific reference interval report for interpretive guidance.N/A

Specimen: serum

No special patient preparation required. Patients should inform their healthcare provider of any recent immunizations, immunosuppressive therapies, or treatments that may affect lymphocyte counts.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

B cells play a critical role in producing antibodies to fight infections and regulate immune responses. Abnormal counts can signal immune deficiencies, chronic inflammation, or malignancies. For example, low counts may raise concerns about infections or treatment side effects, while elevated counts could indicate overactive immune activity or underlying disorders.

Short name

B-Cell Count

Frequently asked questions

What does a normal B-cell count mean for my health?
A normal B-cell count doesn’t guarantee your immune system is healthy—it’s just a snapshot. Your provider will use this result alongside other tests and symptoms to assess your overall health. If your count is outside the expected range, further evaluation may be needed to determine the cause.
How often should I get this test?
Frequency depends on your medical condition. If you have a chronic illness (e.g., HIV, cancer), your provider may order this test regularly to monitor changes. For routine check-ups, it’s usually not recommended unless symptoms suggest it’s needed.
Can diet or supplements affect B-cell counts?
Dietary changes alone won’t directly alter B-cell counts, but certain nutrients (like vitamin D, B12, or zinc) support immune function. Avoiding excessive alcohol or smoking may indirectly improve immune health, but this test alone won’t show those effects.
  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