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Eosinophil Count (Blood)

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

This test measures the number of eosinophils, a type of white blood cell involved in fighting certain infections and allergic reactions.

Quick summary

["Eosinophils help your body respond to allergies and parasitic infections."]

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

Key facts at a glance

LOINC
5785-1
Short code
Eosinophil #/area UrnS HPF
Synonyms
Eosinophil #/area UrnS HPF
Category
chemistry
Sample
urine
Container
Sterile urine container
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
microscopy-light-hpf
Specimen volume
10 mL
Stability
Room temperature: 2h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

What Are Eosinophils?

Eosinophils are a type of white blood cell that play a key role in defending the body against parasites and managing allergic responses. They release chemicals that help fight off harmful organisms and reduce inflammation caused by allergens.

When Might This Test Be Needed?

Your doctor may order this test if you have symptoms like persistent itching, skin rashes, asthma, or unexplained allergic reactions. It can also help diagnose conditions such as parasitic infections, certain types of asthma, or eosinophilic disorders.

What to Expect Before the Test

No special preparation is needed for this blood test. You may be asked to fast for 8–12 hours before the draw if your doctor specifies it, but this is not always required for a simple white blood cell count.

What Happens During the Test?

A healthcare provider will take a small blood sample from a vein in your arm using a needle. The sample is then sent to a lab for analysis to count your eosinophil levels.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Elevated eosinophil counts may suggest conditions like allergic diseases, parasitic infections, certain lung diseases (e.g., asthma), or inflammatory disorders. Low levels might indicate immune suppression or other underlying health concerns, though this is less common.

Short name

Eosinophil Count

Frequently asked questions

Why might my doctor want to check my eosinophil count?
Your doctor may check this count to diagnose or monitor conditions like allergies, asthma, parasitic infections, or rare blood disorders. It can also help guide treatment decisions for certain chronic illnesses.
What are typical reference ranges for eosinophils?
Reference ranges vary by lab and age. Healthy adults typically have eosinophils between 0.04% and 0.75% of total white blood cells, but exact values depend on your lab’s standards.
Can I do anything to affect my eosinophil levels?
Stress, certain medications (like steroids), infections, or allergens can temporarily raise eosinophil counts. Avoiding recent illnesses or allergens may help stabilize results.
  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