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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 infections and respond to allergies and inflammation.

Quick summary

["Eosinophil counts can help diagnose or monitor conditions affecting your immune system or allergies."]

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

Key facts at a glance

LOINC
35062-9
Short code
Eosinophil # Plr
Synonyms
Eosinophil # 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 This Test Is Done

Doctors may order an eosinophil test to check for conditions like allergies, asthma, parasitic infections, or certain types of cancer. It can also help evaluate symptoms such as persistent itching, skin rashes, or unexplained fatigue.

What to Expect Before the Test

No special preparation is needed. You’ll have a small needle inserted into your arm to draw blood, similar to a routine blood draw. The process takes about 5 minutes.

What the Results Mean

Eosinophil counts are usually reported as a percentage of total white blood cells or an absolute count (number per microliter). High levels may indicate allergic reactions, infections, or inflammatory conditions, while low levels might suggest immune suppression or other health concerns.

Common Conditions Monitored

Eosinophil tests are often used to diagnose or track conditions such as asthma, certain types of cancer (like Hodgkin lymphoma), parasitic infections, or autoimmune disorders.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: Eosinophils play a key role in defending against parasites and responding to allergies and chronic inflammation. Elevated counts may signal an active immune response, while persistently low levels could indicate weakened immune function or other systemic issues.

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, or inflammatory conditions. Your doctor may also check levels if you have symptoms like persistent itching, skin rashes, or unexplained weight loss.
What does a low eosinophil count mean?
Low eosinophil counts may suggest immune suppression, certain medications, or underlying health conditions like autoimmune diseases. Your doctor will consider your overall health and symptoms when interpreting results.
Can diet or lifestyle affect eosinophil levels?
While diet and lifestyle factors may influence overall immune function, they typically don’t directly alter eosinophil counts. Avoiding stress or allergens may help manage symptoms if eosinophils are elevated, but this isn’t a direct test result modifier.
  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