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Eosinophil count (per microliter of whole 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 or 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
67829-2
Short code
Eosinophil # Pcar
Synonyms
Eosinophil # Pcar
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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

Your doctor 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 affecting your immune system or blood cells.

What to Expect Before the Test

No special preparation is needed. You’ll have a small needle inserted into your arm or hand to draw blood. It usually takes a few minutes, and you may feel a slight pinch.

What the Results Mean

High eosinophil levels may suggest allergies, asthma, infections, or certain autoimmune diseases. Low levels might indicate immune suppression or other blood disorders. Your doctor will discuss results with you based on your symptoms and medical history.

Common Conditions Linked to Eosinophil Levels

Elevated eosinophils are often seen in allergic reactions, parasitic infections, certain cancers (like lymphoma), or inflammatory conditions. Low levels can occur with immune deficiencies or after certain treatments.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Eosinophils play a key role in defending against parasites and managing allergic responses, but their exact role in chronic diseases like asthma or autoimmune disorders is still being studied. Your doctor will use the results alongside other tests and symptoms to guide care.

Short name

Eosinophil level

Frequently asked questions

What causes eosinophils to be high?
High eosinophil levels can result from allergies, asthma, parasitic infections, certain cancers, or inflammatory diseases. Stress, certain medications, or other underlying health conditions may also play a role.
How long does it take to get results?
Results are typically available within 1 to 3 business days, depending on your lab’s processing time. Your doctor will contact you once they’re ready.
Can diet or exercise affect eosinophil levels?
Diet or exercise alone usually don’t significantly change eosinophil levels, but certain foods (like those high in omega-3s) or supplements (like probiotics) might influence immune responses indirectly. Always discuss any concerns with your doctor.
  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