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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 caused by parasites and play a role in allergic reactions.

Quick summary

["Eosinophil levels help identify infections, allergies, or other conditions affecting your immune system."]

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

Key facts at a glance

LOINC
74405-2
Short code
Eosinophil NFr BldCo
Synonyms
Eosinophil NFr BldCo
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
3 mL
Stability
Room temperature: 4h, Refrigerated: 24h
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

Why This Test Is Done

Your doctor may order this test to diagnose or monitor conditions such as allergic reactions, parasitic infections, certain types of asthma, or inflammatory diseases. It can also help assess how your body is responding to treatments for these conditions.

What to Expect Before the Test

No special preparation is needed for this test. You may have a small needle inserted into your arm to draw blood, similar to a regular blood draw. The process is quick and usually painless.

What the Test Results Mean

Eosinophil counts are typically reported as the number of cells per microliter (cells/µL) of blood. High levels may indicate allergies, infections, or other immune-related conditions, while low levels might suggest certain immune deficiencies or chronic illnesses.

Common Conditions Linked to Eosinophil Levels

Elevated eosinophil counts can be associated with conditions like asthma, allergic reactions, parasitic infections, certain cancers (e.g., lymphoma), or autoimmune diseases. Low eosinophil counts may be linked to conditions like severe infections or certain immune disorders.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Eosinophil blood test

Frequently asked questions

How often will I need this test?
Your doctor will determine how often you need this test based on your symptoms, medical history, and treatment plan. Some patients may need it periodically to monitor their condition, while others may only need it once.
What are the normal ranges for eosinophils?
There are no strict numeric reference ranges provided here since they can vary by lab and individual. Your doctor will interpret the results in the context of your overall health and symptoms.
Can I eat or drink anything before this test?
No dietary restrictions apply to 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