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Lymphocyte Count in Serum or Plasma (Absolute)

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

["Your immune health may depend on keeping lymphocyte levels balanced."]

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

Key facts at a glance

LOINC
9440-9
Short code
Lymphs IgA/lymph NFr WBC
Synonyms
Lymphs IgA/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

Why This Test Might Be Ordered

Doctors may order this test to check for infections, immune system disorders, or conditions like leukemia, HIV, or autoimmune diseases. It can also help monitor treatment responses for certain illnesses.

What to Expect Before the Test

No special preparation is needed. You may have a blood draw from a vein in your arm. If you’re on blood thinners, let your doctor know before the test.

How the Test Works

A small amount of blood is taken and analyzed to count the lymphocytes. This is typically done using an automated blood cell counter or a specialized lab test.

What the Results Mean

Results show the number of lymphocytes per microliter (µL) of blood. Abnormally high or low counts may signal health concerns that need further evaluation.

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.

High lymphocyte counts may indicate an active infection, chronic inflammation, or certain cancers like lymphoma. Low counts can suggest immune deficiencies, severe infections, or treatments that suppress the immune system. Always discuss results with your healthcare provider.

Short name

Absolute Lymphocyte Count

Frequently asked questions

What causes a high lymphocyte count?
High lymphocyte counts can result from infections (like viral or bacterial), certain cancers (such as lymphoma), or immune system disorders. Chronic conditions like rheumatoid arthritis or autoimmune diseases may also play a role.
What causes a low lymphocyte count?
Low lymphocyte counts can occur due to infections, immune system disorders, chemotherapy or radiation therapy, or conditions like HIV/AIDS. Stress, poor nutrition, or certain medications may also lower lymphocyte levels.
How often should I get this test?
Your doctor will determine how often you need this test based on your health condition, symptoms, and treatment plan. Regular monitoring may be necessary if you have a chronic illness or are undergoing treatment that affects your immune system.
  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