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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 your body fight infections and maintain immune function.

Quick summary

["Lymphocytes are key to your immune system and help protect against illness."]

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

Key facts at a glance

LOINC
72219-9
Short code
Lymphocytes #/area UrnS HPF
Synonyms
Lymphocytes #/area UrnS HPF
Category
chemistry
Sample
urine
Container
Sterile urine container
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
microscopy-light-hpf
Specimen volume
10 mL
Stability
Room temperature: 2h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

Why This Test Might Be Ordered

Your healthcare provider may order a lymphocyte count to evaluate your immune system, diagnose conditions like infections, autoimmune diseases, or certain cancers, or monitor treatment responses. It can also help assess conditions affecting white blood cell production or function.

What to Expect Before the Test

No special preparation is needed for this test. You may have a simple blood draw, usually done in a doctor’s office or lab. The process is quick and typically painless.

What the Test Results Mean

Results are usually reported as a count of lymphocytes per microliter (µL) of blood. While reference ranges vary by lab, lower than expected counts may suggest immune suppression, higher counts could indicate infection, inflammation, or other conditions. Your provider will interpret results in the context of your overall health.

Common Conditions Affecting Lymphocyte Counts

Changes in lymphocyte levels can signal conditions like chronic infections, certain cancers (e.g., lymphoma), autoimmune diseases (e.g., lupus), or side effects from treatments like chemotherapy.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Lymphocyte counts are critical for diagnosing and managing immune-related disorders. Low counts may indicate weakened immunity, while elevated counts can point to overactive immune responses or underlying health issues. Regular monitoring helps track immune health and treatment effectiveness.

Short name

Lymphocyte Count

Frequently asked questions

What causes a low lymphocyte count?
Low lymphocyte counts can result from infections (e.g., HIV), certain medications, autoimmune diseases, or conditions that affect bone marrow function. Chronic stress, malnutrition, or severe illness may also contribute.
What causes a high lymphocyte count?
High lymphocyte counts may occur with infections (e.g., viral), inflammatory conditions, or certain cancers. Stress, allergies, or immune system overactivity can also lead to elevated levels.
How often should I get this test?
Frequency depends on your health status. Your provider may recommend this test periodically if you have an ongoing condition affecting immunity, or as part of routine check-ups for certain risk factors.
  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