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Lymphocyte count (peripheral blood)

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

This test measures the number of lymphocytes, a type of white blood cell, in your blood. Lymphocytes help fight infections and are part of your immune system.

Quick summary

["Lymphocytes help protect your body against infections and diseases."]

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

Key facts at a glance

LOINC
97595-3
Short code
CD3CD4RESP
Synonyms
CD3+CD4+ Cells/lymph NFr Lower resp FC
Category
chemistry
Sample
serum
Container
Sterile, leak-proof container for bronchoalveolar lavage (BAL) or bronchial washings; transfer to RPMI or PBS transport medium recommended. Heparinized or EDTA tubes acceptable for cell suspension preservation.
Units
N/A
Ref low
35
Ref high
70
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
flow-cytometry
CPT
86360
SNOMED
30366009
Specimen volume
Minimum 5–10 mL of lower respiratory specimen (BAL fluid, bronchial washings, or bronchoalveolar lavage); larger volumes (30–50 mL) preferred for adequate lymphocyte yield.
Stability
Specimen should be processed within 2–4 hours of collection for optimal viability. If delayed, refrigerate at 2–8°C for up to 24 hours; do not freeze. Transport on wet ice if external laboratory referral is required.
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

Why Is This Test Done?

Doctors may order a lymphocyte count to evaluate your immune system, diagnose conditions like infections, cancers (e.g., lymphoma), or autoimmune diseases, or monitor treatment effectiveness. It can also help assess conditions affecting the bone marrow or blood cells.

What Does a Low or High Lymphocyte Count Mean?

A low lymphocyte count may indicate immune suppression, infections, or certain cancers. A high count could suggest chronic infections, certain cancers, or overactive immune responses. However, results depend on your overall health and medical history.

How Is This Test Performed?

A blood sample is drawn from a vein, usually in your arm. The sample is sent to a lab, where it is analyzed to count the number of lymphocytes. This is typically done using automated blood cell counters.

What Should You Expect Before the Test?

No special preparation is usually needed. You may have some mild discomfort or bruising at the injection site, but this is normal. Avoid eating or drinking for a short time before the test if instructed by your healthcare provider.

Reference range

Adult reference values for CD3+CD4+ (T-helper) cells in respiratory specimens have not been firmly established; results must be interpreted alongside peripheral blood CD4 counts. Bronchoalveolar lavage (BAL) reference (immunocompetent adults): approximately 35–70% of lymphocytes; absolute counts vary with lavage recovery volume. Peripheral blood adult reference range: 38.3–69.6% of lymphocytes; 410–1,590 cells/µL.N/A

Specimen: serum

No fasting required. If specimen is collected via bronchoscopy with bronchoalveolar lavage, patient should follow standard pre-procedural instructions (typically NPO for 4–8 hours prior to sedation). Inform clinician of any active respiratory infection, recent corticosteroid or immunosuppressive therapy, and HIV status prior to collection.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: Lymphocyte Counts Can Indicate Underlying Health Conditions

Short name

Lymphocyte count

Frequently asked questions

What Are My Results Meant to Tell Me About My Health?
Your results will be compared to standard reference ranges provided by your healthcare provider. While absolute numbers can indicate potential issues, they are often interpreted alongside other symptoms, test results, and medical history to guide diagnosis and treatment plans.
How Often Should I Get This Test?
Frequency depends on your medical condition and treatment plan. Your doctor will determine how often you need this test based on your specific needs, such as monitoring chronic illnesses or response to therapy.
Can I Avoid This Test?
While you can’t prevent the test itself, you can discuss alternatives or ask your doctor about reasons for the test to ensure it aligns with your health goals and concerns.
  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