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Lymphocyte Count in Whole 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

["Lymphocyte count helps assess your immune health and response to treatments."]

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

Key facts at a glance

LOINC
11031-2
Short code
Lymphocytes NFr Fld
Synonyms
Lymphocytes NFr Fld
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
86430
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 Is This Test Done?

Doctors may order a lymphocyte count to evaluate symptoms like frequent infections, fatigue, or unexplained weight loss. It can also help diagnose conditions such as immune deficiencies, certain cancers, or autoimmune disorders.

What to Expect Before the Test

No special preparation is needed for this blood test. You may have a small needle inserted into your arm to draw a blood sample, which usually causes only minor discomfort.

What the Results Mean

Results are typically reported as the absolute number of lymphocytes per microliter (µL) of blood. Abnormal levels may suggest immune system issues, infections, or other health concerns that require further medical evaluation.

Common Conditions Affecting Results

Low lymphocyte counts (lymphocytopenia) can occur with infections, certain medications, or immune disorders. High counts (lymphocytosis) may indicate chronic infections, inflammation, or certain cancers.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Lymphocyte Count

Frequently asked questions

What causes a low lymphocyte count?
Low lymphocyte counts can result from infections (like HIV or COVID-19), certain medications (e.g., chemotherapy), autoimmune diseases, or conditions affecting bone marrow function.
What causes a high lymphocyte count?
High lymphocyte counts may be linked to chronic infections (e.g., mononucleosis), inflammatory diseases, or certain cancers (e.g., lymphoma). Stress or emotional factors can also temporarily elevate lymphocyte levels.
How often should I get this test?
Frequency depends on your health status. Doctors may recommend periodic testing if you have a chronic condition, undergo treatment for cancer or immune disorders, or experience recurring infections.
  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