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Eosinophil count in serum (qualitative)

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

This test checks for the presence of eosinophils, a type of white blood cell, in your blood serum. Eosinophils help fight certain infections and respond to allergies or inflammatory conditions.

Quick summary

["Eosinophils may rise in response to allergies, infections, or inflammatory diseases."]

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

Key facts at a glance

LOINC
9522-4
Short code
E histolyt IgG Ser IA-aCnc
Synonyms
E histolyt IgG Ser IA-aCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ia
CPT
82784
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 Eosinophil Count Used For?

Eosinophil counts are often used to diagnose or monitor conditions such as allergic reactions, parasitic infections, asthma, or certain autoimmune diseases. They can also help guide treatment decisions for conditions like eosinophilic esophagitis or chronic urticaria.

When Might You Need This Test?

Your doctor may order this test if you have symptoms like persistent itching, skin rashes, digestive issues, or unexplained fatigue. It’s also used in research or specialized clinical settings to assess immune responses.

How Is the Test Performed?

A blood sample is drawn from a vein, typically in your arm. The serum portion is then analyzed to detect eosinophil presence using a qualitative method (often visual or automated cell counting).

What Are Common Results?

Results are qualitative (positive/negative) rather than numeric. A positive result indicates elevated eosinophils, which may signal an underlying condition requiring further evaluation.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Eosinophil Screen (Serum)

Frequently asked questions

Why was this test ordered?
Your doctor may have suspected an allergic reaction, infection, or inflammatory condition based on your symptoms or medical history. This test helps confirm or guide further diagnosis.
What do elevated eosinophil levels mean?
Elevated eosinophils can indicate conditions like asthma, allergies, parasitic infections, or certain autoimmune diseases. Your doctor will discuss next steps based on your overall health and test results.
Can I eat or drink before this test?
No special preparation is needed for this test. However, follow your doctor’s instructions regarding fasting or medications if applicable.
  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