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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 important for fighting infections and maintaining immunity.

Quick summary

["Lymphocytes help protect your body from illness and disease."]

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

Key facts at a glance

LOINC
9443-3
Short code
Lymphs IgM/lymph NFr WBC
Synonyms
Lymphs IgM/lymph NFr WBC
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
4.5
Ref high
11
Critical range
2 N/A – 30 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
85004
SNOMED
900000000000003002
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

What Is a Lymphocyte Count?

Lymphocytes are a subset of white blood cells that play a key role in your immune system. They help your body recognize and fight off bacteria, viruses, and other invaders. This test checks how many lymphocytes are present in your blood, which can help doctors assess your immune health or identify conditions like infections, autoimmune diseases, or certain cancers.

Why Might You Need This Test?

Your doctor may order a lymphocyte count to evaluate symptoms such as frequent infections, unexplained fatigue, swollen lymph nodes, or other signs of immune system issues. It can also be part of a routine blood test or used to monitor conditions like leukemia, HIV, or other immune disorders.

How Is the Test Performed?

A small amount of blood is drawn from a vein, usually in your arm, using a needle. The blood sample is then analyzed in a lab to count the number of lymphocytes. This is typically done as part of a complete blood count (CBC) test.

What Do the Results Mean?

Results are usually reported as a count of lymphocytes per microliter (µL) of blood. While specific reference ranges can vary by lab, a lower than expected count may suggest immune suppression, while a higher count could indicate an active infection, inflammation, or other conditions.

Reference range

Adult: 4.5-11.0 x 10^9/LN/A

Specimen: serum

No special preparation required. Stay well hydrated.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Lymphocyte Count

Frequently asked questions

What could high or low lymphocyte counts indicate?
High lymphocyte counts may be seen in chronic infections, certain cancers (like lymphoma), or immune system responses such as allergies or autoimmune reactions. Low lymphocyte counts can signal immune deficiencies, HIV/AIDS, certain chemotherapy treatments, or other conditions that weaken the immune system.
How often should I get this test?
The frequency depends on your health, symptoms, and any ongoing medical conditions. Your doctor will determine if and how often you need this test based on your individual needs, such as monitoring treatment for a chronic illness or evaluating symptoms of infection or immune dysfunction.
Can lifestyle or diet affect lymphocyte counts?
Yes, lifestyle factors like diet, stress, sleep, and exercise can influence immune function. Eating a balanced diet rich in vitamins and minerals, managing stress, and maintaining good sleep hygiene may support normal lymphocyte levels, but this test alone does not diagnose or treat conditions—consult your doctor for guidance.
  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