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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 your body defend against parasites and respond to allergic reactions."]

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

Key facts at a glance

LOINC
30379-2
Short code
Eosinophil NFr Plr
Synonyms
Eosinophil NFr Plr
Category
chemistry
Sample
fluid
Container
Sterile tube
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
2-5 mL
Stability
Room temperature: 2h, Refrigerated: 24h
Hemolysis max
300
TAT
4–24 hours
Order
routine

Why Is This Test Done?

Your healthcare provider may order this test to check for conditions like allergies, asthma, parasitic infections, or certain types of cancer. It can also help diagnose or monitor conditions like eosinophilic esophagitis, chronic eosinophilic leukemia, or other inflammatory diseases.

What to Expect Before the Test

No special preparation is usually needed. You may have a small needle inserted into your arm to draw blood. The process takes about 5 minutes, and you can resume normal activities afterward.

What the Results Mean

Eosinophil counts can vary. High levels may suggest allergic reactions, infections, or certain diseases. Low levels might indicate immune system issues or other health concerns. Always discuss your results with your healthcare provider.

Common Conditions Affecting Eosinophil Levels

Elevated eosinophil counts can be linked to allergies, asthma, parasitic infections, certain cancers (like lymphoma or leukemia), and inflammatory conditions. Low levels may be associated with autoimmune diseases or other immune deficiencies.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Eosinophils play a role in allergic responses and fighting parasitic infections. High counts can indicate ongoing inflammation or immune system activation, while low counts may suggest weakened immune function or other underlying health issues. Your provider will use the results alongside other factors to guide diagnosis and treatment.

Short name

Eosinophil Level

Frequently asked questions

What causes eosinophil levels to be high?
High eosinophil levels can be caused by allergies, asthma, parasitic infections, certain cancers, or inflammatory conditions like eosinophilic esophagitis. Stress, certain medications, and some autoimmune diseases may also play a role.
What does it mean if my eosinophil count is low?
Low eosinophil counts may indicate immune system suppression, certain infections, or autoimmune disorders. It’s important to discuss symptoms and other test results with your healthcare provider to understand the cause.
Can diet or lifestyle affect eosinophil levels?
Diet and lifestyle factors like stress, diet changes, or certain medications can influence white blood cell counts, including eosinophils. However, this test measures a specific cell type, and results are interpreted in the context of your overall health and symptoms.
  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