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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

["Eosinophil counts help diagnose and monitor conditions like allergies, infections, and certain blood disorders."]

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

Key facts at a glance

LOINC
16817-9
Short code
E histolyt Ab Ser Ql ID
Synonyms
E histolyt Ab Ser Ql ID
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
immune-diffusion
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 healthcare provider may recommend this test if you have symptoms like persistent itching, skin rashes, asthma, or unexplained weight loss. It could also be part of a broader blood workup for conditions like parasitic infections, autoimmune diseases, or eosinophilic disorders.

What to Expect Before the Test

No special preparation is needed for this test. You’ll have a small needle inserted into your arm to draw blood, similar to a regular blood draw. The process usually takes a few minutes.

What the Test Results Mean

Results are typically reported as the number of eosinophils per microliter of blood. Elevated levels may indicate allergies, infections, or certain inflammatory or autoimmune conditions. Lower-than-normal levels might suggest certain blood disorders or immune system issues.

Common Conditions Linked to Eosinophil Counts

High eosinophil counts can be associated with allergies, asthma, parasitic infections, certain cancers (like Hodgkin lymphoma), and autoimmune diseases. Low counts may be linked to conditions like aplastic anemia or certain viral infections.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: Eosinophils Serve Multiple Roles

Short name

Eosinophil blood count

Frequently asked questions

What causes my eosinophil count to be higher than usual?
Elevated eosinophil counts can result from allergies, asthma, parasitic infections, certain medications, or conditions like eosinophilic granulomatosis with polyangiitis. If your levels are persistently high, your doctor may investigate further to rule out underlying causes like cancer or autoimmune disorders.
How often should I get this test?
The frequency depends on your symptoms and medical history. If you have a known condition like asthma or allergies, your doctor may order this test periodically to monitor your condition. If you’re asymptomatic, it’s usually not routine unless part of a broader evaluation.
Can diet or lifestyle affect eosinophil counts?
While diet and lifestyle factors like stress or certain foods may influence inflammation indirectly, they don’t directly affect eosinophil counts. However, managing allergies or chronic conditions with diet and lifestyle changes can help support overall health.
  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