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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 certain infections and respond to allergies and inflammation.

Quick summary

["Eosinophils help your body fight parasites, allergies, and some infections, but high or low levels may signal health concerns."]

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

Key facts at a glance

LOINC
30382-6
Short code
Eosinophil NFr Stl
Synonyms
Eosinophil NFr Stl
Category
chemistry
Sample
stool
Container
Clean container
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
5 g
Stability
Refrigerated: 24h, Frozen: 7d
TAT
4–24 hours
Order
routine

Why This Test Is Done

Your doctor may order this test to diagnose or monitor conditions like allergies, asthma, parasitic infections, or certain autoimmune diseases. It can also help assess responses to treatments or check for hidden inflammation.

What to Expect Before the Test

No special preparation is needed. A blood sample is taken from a vein, usually in your arm, and sent to a lab for analysis. The process takes a few minutes.

What the Results Mean

Eosinophil counts vary naturally. High levels may indicate allergies, infections, or conditions like asthma or certain cancers. Low levels might suggest immune suppression or other health issues. Always discuss your results with your healthcare provider.

Common Conditions Linked to Results

Elevated eosinophil counts can be linked to allergies, parasitic infections, certain lung diseases (like asthma), or inflammatory conditions. Low levels may be seen in immune disorders or after certain treatments.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Eosinophils play a role in allergic reactions and fighting parasites, but their exact function in chronic conditions like asthma or autoimmune diseases is still being studied. High or low levels can signal underlying health concerns that need further evaluation.

Short name

Eosinophil Level

Frequently asked questions

What causes eosinophil levels to be high?
High eosinophil counts can result from allergies, asthma, parasitic infections, certain cancers (like leukemia), or inflammatory conditions. Stress, certain medications, or other underlying health issues may also play a role.
What does it mean if my eosinophil count is low?
Low eosinophil counts may indicate immune suppression, certain infections, or conditions affecting white blood cell production. It can also occur with long-term steroid use or other treatments.
Can diet or lifestyle affect eosinophil levels?
While diet and lifestyle factors like stress or exercise can influence white blood cell counts indirectly, they don’t directly affect eosinophil levels. Always follow your doctor’s advice regarding test-related preparations.
  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