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Eosinophil count (qualitative or semi-quantitative blood smear evaluation)

Published: August 9, 2026Updated: August 16, 2026

This test checks 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 levels can signal allergic reactions, infections, or other immune responses."]

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

Key facts at a glance

LOINC
68403-5
Short code
Eosinophil NFr Vitf Manual
Synonyms
Eosinophil NFr Vitf Manual
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
manual-count
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 recommend this test if you have symptoms like persistent itching, skin rashes, asthma, or unexplained allergies. It could also be used to monitor conditions like asthma, parasitic infections, or certain autoimmune diseases.

What to Expect Before the Test

No special preparation is needed. You’ll have a small needle inserted into your arm to draw a small amount of blood. This is quick and usually painless.

What Happens During the Test

The blood sample is examined under a microscope by a trained lab technician. They look for eosinophils, which appear as a specific cell type in the blood smear. The result may be qualitative (yes/no presence) or semi-quantitative (approximate count).

What the Results Mean

Results are not given as a single number but rather as a qualitative assessment (e.g., ‘elevated,’ ‘normal,’ or ‘not detected’). High eosinophil counts may indicate allergies, infections, or inflammatory conditions.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Elevated eosinophils can signal allergic reactions, parasitic infections, certain lung diseases (like asthma or eosinophilic pneumonia), or autoimmune disorders. Low or normal levels may suggest typical immune function without significant issues. Always discuss results with your doctor for personalized interpretation.

Short name

Eosinophil test

Frequently asked questions

What causes eosinophils to be high?
High eosinophil counts can result from allergies, asthma, parasitic infections, certain medications, or inflammatory conditions. Chronic conditions like eosinophilic esophagitis or certain cancers may also be associated with elevated levels.
How long does it take to get results?
Results are typically available within 1 to 3 business days, depending on lab processing times. Your doctor will contact you with the findings once they are ready.
Can I eat or drink before this test?
No special diet or fasting is required for this test. You can eat and drink normally before having your blood drawn.
  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