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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 immune system fight infections and diseases.

Quick summary

["Lymphocytes help protect your body against infections and support immune function."]

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

Key facts at a glance

LOINC
35097-5
Short code
Lymphocytes # Prt
Synonyms
Lymphocytes # Prt
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

Why This Test Might Be Ordered

Your healthcare provider may order this test to check for signs of immune system issues, such as infections, inflammation, or conditions like leukemia, lymphoma, or autoimmune diseases. It can also help monitor treatment responses for certain illnesses.

What to Expect Before the Test

No special preparation is needed for this test. You’ll have a small needle inserted into your arm or hand to draw a blood sample. The process usually takes a few minutes, and you may feel a slight pinch or discomfort.

What the Results Mean

Results are typically 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, while higher counts could indicate infection, inflammation, or certain blood disorders.

Common Conditions Affecting Lymphocyte Counts

Low lymphocyte counts may be linked to conditions like HIV/AIDS, chemotherapy, or severe infections. High counts can occur with chronic infections (e.g., mononucleosis), certain cancers, or overactive immune responses.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Lymphocyte counts help diagnose and guide treatment for immune-related disorders, infections, and blood cancers. They’re also used to assess how well your immune system is functioning after treatments like chemotherapy or organ transplants.

Short name

Lymphocyte Count

Frequently asked questions

What causes my lymphocyte count to change over time?
Several factors can influence lymphocyte counts, including infections, stress, medications (like steroids), chronic illnesses, or even recent vaccinations. Your provider will discuss any changes with you based on your medical history.
Is there anything I should avoid before this test?
No specific restrictions apply, but inform your provider if you’re taking medications that affect your immune system or have recently had a significant illness.
Can lifestyle changes impact my lymphocyte count?
Yes, lifestyle factors like diet, sleep, and exercise can influence immune function. While not directly measured in this test, maintaining a healthy lifestyle may support overall immune health.
  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