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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 caused by parasites and play a role in allergic reactions.

Quick summary

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

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

Key facts at a glance

LOINC
31811-3
Short code
E histolyt Ag Stl-aCnc
Synonyms
E histolyt Ag Stl-aCnc
Category
chemistry
Sample
stool
Container
Clean container
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
5 g
Stability
Refrigerated: 24h, Frozen: 7d
TAT
4–24 hours
Order
routine

Why This Test Is Done

Your doctor may order this test if you have symptoms like persistent itching, skin rashes, unexplained weight loss, or if you’ve been diagnosed with an allergy, asthma, or parasitic infection. It can also help evaluate conditions like eosinophilic esophagitis or certain blood cancers.

What to Expect Before the Test

No special preparation is needed. You’ll have a small needle inserted into a vein (usually in your arm), and blood will be drawn into a tube. The process takes a few minutes, and you may feel a slight pinch or discomfort.

What the Results Mean

Results are typically reported as the number of eosinophils per microliter (µL) of blood. High levels may indicate allergies, infections, or inflammatory conditions, while very low levels might suggest immune suppression or other blood disorders.

Common Conditions Linked to Abnormal Results

Elevated eosinophil counts can be linked to conditions like allergic reactions, asthma, parasitic infections, eosinophilic granulomatosis with polyangiitis (EGPA), or certain cancers. Low counts may suggest immune deficiencies or medications that suppress white blood cells.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Eosinophil blood count

Frequently asked questions

How long does it take to get my eosinophil blood count results?
Results are usually available within 1 to 3 business days, depending on your lab. Your doctor will discuss them with you during your follow-up visit.
Can I eat or drink anything before this test?
No special diet or fasting is required for this test. You can eat and drink normally before your appointment.
What are the most common causes of high eosinophil counts?
High eosinophil counts can be caused by allergies, asthma, parasitic infections, certain medications, or inflammatory conditions like eosinophilic esophagitis.
  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