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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 maintain immune function.

Quick summary

["Your immune system’s white blood cell count, specifically lymphocytes, is assessed to check for infections, immune disorders, or other health concerns."]

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

Key facts at a glance

LOINC
100854-9
Short code
Lymphocytes Bld MC IA-NFr
Synonyms
Lymphocytes Bld MC IA-NFr
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ia
Specimen volume
3 mL
Stability
Room temperature: 4h, Refrigerated: 24h
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

Why This Test Matters

Lymphocytes are part of your immune system and play a key role in defending your body against infections and diseases. This test helps doctors monitor your immune health, especially if you have conditions like HIV, cancer, or autoimmune disorders. Abnormal counts may indicate infections, inflammation, or immune system issues.

When You Might Need This Test

Your doctor may order this test if you have symptoms like frequent infections, fatigue, swollen lymph nodes, or if you’re undergoing treatment for conditions that affect the immune system. It’s also part of routine blood work for certain health checks.

What to Expect Before the Test

No special preparation is needed for this test. You’ll have a small needle inserted into your arm, and a few drops of blood will be drawn into a tube. The process usually takes just a few minutes.

What the Results Mean

Results are reported as a count of lymphocytes per microliter (µL) of blood. While reference ranges vary by lab, very high or very low counts may signal potential health concerns that your doctor will discuss with you.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Lymphocyte Count

Frequently asked questions

What causes high or low lymphocyte counts?
High lymphocyte counts can occur with infections (like viral or bacterial), certain cancers (like lymphoma), or immune system disorders. Low counts may indicate infections, immune suppression (e.g., from medications or HIV), or other conditions like leukemia.
How often should I get this test?
Your doctor will determine how often you need this test based on your health status, treatments, or symptoms. Regular monitoring may be needed if you have chronic conditions or are undergoing treatments that affect your immune system.
Can lifestyle changes affect lymphocyte counts?
Yes, lifestyle factors like diet, stress, sleep, and exercise can influence immune function. Maintaining a balanced diet, staying hydrated, and managing stress may support healthy lymphocyte levels, but this test alone won’t show lifestyle impacts.
  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