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Eosinophil Absolute Count (Serum/Plasma)

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

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

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

Key facts at a glance

LOINC
57431-9
Short code
ENA Ab Ser Ql IB
Synonyms
ENA Ab Ser Ql IB
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ib
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

What Is an Eosinophil Count Used For?

Doctors may order this test to diagnose or monitor conditions like allergies, asthma, parasitic infections, or certain autoimmune diseases. It can also help evaluate symptoms such as persistent itching, skin rashes, or unexplained weight loss.

When Might You Need This Test?

You might need an eosinophil count if you have symptoms like chronic coughing, unexplained skin reactions, or if your doctor suspects an allergic reaction or parasitic infection. It’s also used in some cancer screenings or to check for conditions like eosinophilic esophagitis.

How Is the Test Performed?

A small blood sample is taken from a vein, usually in your arm. The blood is then analyzed in a lab to count the number of eosinophils among your white blood cells.

What Do the Results Mean?

Results are typically reported as the absolute number of eosinophils per microliter of blood. High levels may indicate allergies, infections, or other conditions affecting eosinophil production or release. Low levels might suggest certain immune disorders or chronic illnesses.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Eosinophil Count

Frequently asked questions

Why did my doctor order this test?
Your doctor may have ordered this test to investigate symptoms like persistent itching, skin rashes, unexplained weight loss, or breathing difficulties. It could also be part of a broader evaluation for allergies, infections, or other conditions affecting eosinophils.
What are typical reference ranges for eosinophil counts?
Reference ranges vary by lab and individual health. Generally, healthy adults may have between 0 to 500 cells per microliter, but these numbers can shift with age, health conditions, or medications.
Can food or medications affect eosinophil counts?
Some medications (like steroids) or certain foods (e.g., allergens) may temporarily influence eosinophil levels. If you’re taking medications, let your doctor know to avoid false 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