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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.

Quick summary

["Eosinophil levels can indicate 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
30378-4
Short code
Eosinophil NFr Nose
Synonyms
Eosinophil NFr Nose
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 is this test done?

Your doctor may order this test to check for conditions like allergic reactions, parasitic infections, asthma, or other immune-related disorders. It can also help monitor treatment progress for certain conditions.

What does a high or low eosinophil count mean?

Elevated eosinophil counts may suggest allergies, asthma, parasitic infections, or certain autoimmune diseases. Low counts might indicate infections, bone marrow disorders, or immune suppression.

How is this test performed?

A small blood sample is drawn from a vein, usually in your arm. The blood is then analyzed in a lab to count eosinophils using automated technology.

What do my results mean?

Results are compared to standard ranges for healthy adults. While reference ranges can vary by lab, abnormal counts may prompt further testing or evaluation of symptoms.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical significance: Eosinophils play a key role in combating parasitic infections, allergic responses, and certain inflammatory conditions. Elevated levels can signal ongoing immune activity, while low levels may indicate suppressed immune function or other underlying issues.

Short name

Eosinophil level

Frequently asked questions

What causes eosinophil levels to change?
Changes can occur due to infections (like parasites or fungal), allergies, asthma, autoimmune diseases, or certain medications. Stress, diet, or recent illness may also temporarily affect counts.
How often should I get this test?
Frequency depends on your health condition and doctor’s recommendations. Some patients get it yearly or more often if managing chronic conditions like asthma or allergies.
Can lifestyle changes affect eosinophil counts?
Yes—stress, diet (especially high-sugar or processed foods), exercise, and certain medications may influence eosinophil levels. Discuss lifestyle adjustments with your doctor if needed.
  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