Lymphocyte Count (Peripheral Blood)
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.
["Your immune system’s white blood cell defenders are checked here."]
Key facts at a glance
- LOINC
- 26481-2
- Short code
- Lymphocytes NFr Plr
- Synonyms
- Lymphocytes NFr Plr
- Category
- chemistry
- Sample
- fluid
- Container
- Sterile tube
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Specimen volume
- 2-5 mL
- Stability
- Room temperature: 2h, Refrigerated: 24h
- Hemolysis max
- 300
- TAT
- 4–24 hours
- Order
- routine
Why This Test Is Done
Doctors may order a lymphocyte count to diagnose or monitor conditions affecting your immune system, such as infections, autoimmune diseases, or certain cancers. It can also help assess how well your body is responding to treatments like chemotherapy or immune-modifying therapies.
What to Expect Before the Test
No special preparation is needed. 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 brief pinch or slight discomfort. If you’re on blood thinners, let your doctor know before the test.
What the Results Mean
Results are typically reported as a count of lymphocytes per microliter (µL) of blood. While reference ranges vary by lab, low or high counts may signal underlying health concerns, such as infections, immune deficiencies, or certain cancers. Your doctor will interpret the results in the context of your overall health.
Common Conditions Affecting Lymphocyte Counts
Low lymphocyte counts (lymphocytopenia) might occur with infections, certain medications, or conditions like HIV/AIDS. High counts (lymphocytosis) can be seen in chronic infections, some cancers, or inflammatory diseases. Your doctor will consider symptoms and other test results to determine the cause.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Lymphocyte counts are critical for diagnosing and managing immune-related disorders. Abnormal levels can indicate immune system dysfunction, infections, or underlying diseases that require targeted treatment. Regular monitoring helps track how well your immune response is functioning over time.
Short name
Lymphocyte Count
Frequently asked questions
What causes a low lymphocyte count?
What causes a high lymphocyte count?
How often should I get this test?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
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.
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