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Eosinophil count (serum-based differential blood analysis)

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 and inflammation.

Quick summary

["Eosinophils help protect your body against parasites and allergic reactions, but elevated levels may signal underlying conditions."]

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

Key facts at a glance

LOINC
109361-6
Short code
E histolyt IgG Msmt Ser
Synonyms
E histolyt IgG Msmt Ser
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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

Why This Test Is Done

Doctors may order this test to investigate symptoms like persistent itching, skin rashes, asthma, or chronic sinusitis. It can also help diagnose conditions such as allergies, parasitic infections, or certain autoimmune diseases.

What to Expect Before the Test

No special preparation is needed. A blood sample is drawn from a vein, usually in your arm. The test is quick and typically done at a lab or clinic.

Possible Results and Their Meaning

Results are reported as the absolute count of eosinophils per microliter (µL) of blood. High levels (elevated eosinophil count) may indicate allergies, infections, or inflammatory conditions. Low levels may suggest immune suppression or other health concerns.

Common Conditions Linked to Eosinophil Levels

Elevated eosinophil counts can be associated with allergies, asthma, parasitic infections, certain cancers (like Hodgkin lymphoma), or inflammatory diseases. Low levels may occur with stress, certain medications, or immune disorders.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Eosinophil level

Frequently asked questions

What does an elevated eosinophil count mean?
What does an abnormal eosinophil count indicate?
Can diet or lifestyle affect eosinophil levels?
How often should I get this test?
The frequency depends on your symptoms and medical history. Your doctor may recommend retesting if you have ongoing allergic symptoms, chronic conditions, or if you’re being treated for a suspected infection.
If your results are abnormal, your doctor will review them with you and may suggest additional tests or treatments. They’ll also consider your overall health and symptoms to determine the next steps.
  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