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Eosinophil count (absolute)

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.

Quick summary

["Eosinophil counts help diagnose and monitor conditions like allergies, infections, and certain blood disorders."]

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

Key facts at a glance

LOINC
20819-9
Short code
E coli K99 Islt Ql Aggl
Synonyms
E coli K99 Islt Ql Aggl
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
aggl
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 healthcare provider may order this test if you have symptoms like persistent itching, skin rashes, asthma, or unexplained fatigue. It could also be used to check for conditions like parasitic infections, certain cancers, or autoimmune diseases.

What to Expect Before the Test

No special preparation is needed. You may have a small needle inserted into your arm or vein to draw blood. If you’re nervous, let your provider know—they can help make it more comfortable.

What the Results Mean

Elevated eosinophil counts may indicate allergies, infections, or inflammatory conditions. Lower-than-normal counts might suggest immune system issues or certain blood disorders. Your provider will discuss results in relation to your symptoms and medical history.

Common Conditions Monitored

This test is often used to track conditions like asthma, eosinophilic esophagitis, parasitic infections, or certain types of leukemia. It can also help guide treatment decisions for allergies or autoimmune disorders.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Eosinophil count

Frequently asked questions

How often will I need this test?
Your provider will determine how often you need retests based on your symptoms, treatment plan, or ongoing health concerns. Some conditions require regular monitoring, while others may only need a one-time check.
Can I eat or drink before the test?
You can eat and drink normally unless your provider specifies otherwise. Blood tests don’t require fasting, so no special diet is needed.
What if my eosinophil count is outside the expected range?
If your results are abnormal, your provider will review them with you and may recommend further testing or adjustments to your treatment plan. They’ll explain what the results mean in the context of your health.
  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