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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 infections and respond to allergies and 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
106917-8
Short code
Eosinophil NFr BAL
Synonyms
Eosinophil NFr BAL
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 Might You Need This Test?

Your doctor may order this test to check for conditions like allergies, asthma, parasitic infections, or certain types of cancer. It can also help monitor treatment progress for conditions affecting eosinophils.

What to Expect Before the Test

No special preparation is needed. You’ll have a small needle inserted into your arm, and a small amount of blood will be drawn. This is usually done in a doctor’s office or lab.

What the Results Mean

Results show the number of eosinophils in your blood. High levels may indicate allergies, infections, or other health issues. Low levels might suggest immune system problems or certain medications.

Common Conditions Linked to Eosinophil Levels

High eosinophil counts can be linked to allergies, asthma, parasitic infections, or autoimmune diseases. Low levels may be associated with certain infections, immune disorders, or medications.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Eosinophil Blood Count

Frequently asked questions

What causes eosinophils to be high in my blood?
Elevated eosinophils can be due to allergies, asthma, parasitic infections, certain cancers (like leukemia), or inflammatory conditions. Your doctor may investigate further based on your symptoms and medical history.
How long does it take to get my test results?
Results are typically available within 1 to 3 business days, depending on your lab. Your doctor will contact you with the final report.
Can I eat or drink before this test?
No special diet is required. You can eat and drink normally before the blood draw, but avoid caffeine if it affects your blood pressure or heart rate.
  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