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Lymphocyte count (manual differential blood count)

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 are key to your immune response; this test helps assess your immune health."]

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

Key facts at a glance

LOINC
71634-0
Short code
Lymphocytes NFr.DF Prt Manual
Synonyms
Lymphocytes NFr.DF Prt Manual
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
manual-count
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 infections, immune system disorders, or conditions like leukemia, lymphoma, or HIV. It can also help monitor treatment responses for certain diseases.

What to Expect Before the Test

No special preparation is needed. You’ll typically have a small needle inserted into your arm to draw blood. If you’re on blood-thinning medication, let your provider know before the test.

What the Test Results Mean

Lymphocyte counts can vary based on health, age, and activity level. High or low counts may signal infections, immune issues, or other health concerns. Your provider will interpret results in relation to your overall health.

Common Conditions Affecting Lymphocyte Counts

Changes in lymphocyte counts can occur with infections (like colds or flu), autoimmune diseases (such as lupus or rheumatoid arthritis), or chronic illnesses like HIV/AIDS. Cancerous conditions, like lymphoma or leukemia, may also alter lymphocyte levels.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Lymphocyte counts are critical for diagnosing and managing immune-related conditions. Elevated counts might indicate overactive immune responses, while low counts could signal weakened immunity, needing further investigation or treatment adjustments.

Short name

Lymphocyte count

Frequently asked questions

What causes a high lymphocyte count?
A high lymphocyte count can result from infections (like viral or bacterial), certain cancers (such as lymphoma), or immune system disorders. Chronic illnesses or long-term stress may also play a role.
What causes a low lymphocyte count?
Low lymphocyte counts may be linked to infections, immune deficiencies, certain medications, or conditions like HIV/AIDS. Stress, poor nutrition, or chronic illnesses can also contribute.
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 your immune system or if you’re undergoing treatment for a disease that impacts white blood cells.
  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