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Eosinophil Count (Peripheral Blood)

Published: August 9, 2026Updated: August 16, 2026

This test measures the number of eosinophils, a type of white blood cell, in your blood. Eosinophils help fight infections and respond to allergies and inflammation.

Quick summary

["Eosinophils help protect your body from harmful substances and infections."]

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

Key facts at a glance

LOINC
25156-1
Short code
Eosinophil UrnS Ql Micro
Synonyms
Eosinophil UrnS Ql Micro
Category
chemistry
Sample
urine
Container
Sterile urine container
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
microscopy-light
Specimen volume
10 mL
Stability
Room temperature: 2h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

What Is an Eosinophil?

Eosinophils are a type of white blood cell that play a key role in defending the body against parasites, allergens, and certain infections. They release chemicals to combat these threats and help regulate inflammation. When levels are high, it may signal an ongoing immune response or an underlying condition.

Why Might Your Doctor Order This Test?

Your doctor may order an eosinophil count to investigate symptoms like persistent itching, skin rashes, asthma, or unexplained infections. It can also help diagnose conditions such as allergies, parasitic infections, certain cancers (like leukemia), or autoimmune disorders.

When Are Eosinophils Typically High?

Eosinophil levels may rise in response to allergies, asthma, parasitic infections, certain types of cancer, or inflammatory conditions. Chronic high levels could indicate conditions like eosinophilic esophagitis, certain lung diseases, or other systemic disorders.

What Could Low Eosinophils Mean?

Low eosinophil counts might occur with certain infections (like viral or bacterial), immune deficiencies, or medications that suppress white blood cell production. Rarely, it could be linked to genetic disorders or severe stress.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Eosinophil Test

Frequently asked questions

What does an abnormal eosinophil count mean?
An abnormal eosinophil count (either high or low) may not have a single cause. High levels often suggest allergic reactions, infections, or inflammatory diseases, while low levels could indicate immune system issues or certain medications. Your doctor will discuss your symptoms and test results to determine the next steps.
How is this test performed?
This test involves drawing a small amount of blood from a vein in your arm. The blood sample is then analyzed in a lab to count the number of eosinophils, a type of white blood cell. The process usually takes a few minutes and is generally painless.
How often should I get this test?
The frequency of this test depends on your symptoms, medical history, and reasons for testing. Your doctor will determine how often you need it based on your individual health needs, such as monitoring allergies, infections, or other conditions that may affect eosinophil levels.
  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