Skip to content

Eosinophil count in blood (qualitative or semi-quantitative)

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

This test checks the number of eosinophils, a type of white blood cell, in your blood. Eosinophils help fight certain infections and respond to allergies or inflammation.

Quick summary

["Eosinophil levels can signal allergic reactions, infections, or other immune responses."]

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

Key facts at a glance

LOINC
9421-9
Short code
E histolyt Ab Ser ID-aCnc
Synonyms
E histolyt Ab Ser ID-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
immune-diffusion
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 Is Done

Your doctor may order this test to investigate symptoms like persistent itching, skin rashes, asthma, or unexplained allergies. It can also help diagnose conditions such as parasitic infections, certain cancers, or autoimmune disorders where eosinophil counts are elevated.

What to Expect Before the Test

No special preparation is needed. You’ll have a small needle inserted into your arm or hand to draw blood. The process usually takes a few minutes, and you may feel a brief pinch.

What the Results Mean

Results are qualitative (yes/no) or semi-quantitative (approximate levels). High eosinophil counts may indicate allergies, infections, or inflammatory conditions. Low counts might suggest immune suppression or other underlying issues.

Possible Causes of Abnormal Results

Elevated eosinophils can be linked to allergies, asthma, parasitic infections, certain cancers (like lymphoma), or autoimmune diseases. Low eosinophils may occur with stress, certain medications, or immune system disorders.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Eosinophil test

Frequently asked questions

What does a high eosinophil count mean?
A high eosinophil count can signal an allergic reaction, parasitic infection, or chronic inflammatory condition. Your doctor will consider your symptoms and other test results to determine the cause.
How often should I get this test?
This test is typically done as needed based on your symptoms or medical concerns. Follow your doctor’s advice for follow-up testing if results are abnormal.
Can I eat or drink before this test?
No special diet is required. You can eat and drink normally, but avoid smoking or heavy exercise right before your blood draw.
  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