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Eosinophil count (mass concentration in whole blood)

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 linked to immune responses or infections."]

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

Key facts at a glance

LOINC
106984-8
Short code
ECM1 Smn IA-mCnc
Synonyms
ECM1 Smn IA-mCnc
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
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?

Eosinophils are a type of white blood cell that helps your body fight certain infections, such as those caused by parasites, and manage allergic reactions. They are part of your immune system and can become more or less active depending on your health status.

Why Might You Need This Test?

Your doctor may order an eosinophil count to check for conditions like allergies, asthma, parasitic infections, or certain autoimmune diseases. It can also help evaluate symptoms such as persistent coughing, skin rashes, or unexplained fatigue.

When Might Results Be Abnormal?

Elevated eosinophil counts may indicate conditions like allergies, asthma, parasitic infections, or certain cancers. Lower-than-normal counts might suggest immune system issues or other health problems, though this is less common.

How Is This Test Performed?

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

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Eosinophil counts are important for diagnosing and managing conditions affecting the immune system. High levels can signal allergic reactions, parasitic infections, or inflammatory diseases, while low levels may indicate rare immune deficiencies or other systemic issues. Always discuss results with your healthcare provider for personalized interpretation.

Short name

Eosinophil count

Frequently asked questions

What causes eosinophil counts to be high?
High eosinophil counts can be caused by allergies, asthma, parasitic infections, certain cancers (like Hodgkin lymphoma), or other inflammatory or autoimmune conditions. Chronic conditions such as eosinophilic esophagitis or certain medications may also play a role.
What does it mean if my eosinophil count is low?
Low eosinophil counts are less common and may suggest rare immune deficiencies or conditions affecting white blood cell production. In some cases, it could indicate bone marrow disorders or other systemic health concerns. Your doctor will consider your overall health and symptoms to interpret results.
Can lifestyle changes affect eosinophil counts?
While lifestyle factors like diet, stress, or exercise can influence overall immune function, they typically do not directly alter eosinophil counts. However, managing known conditions (like allergies or asthma) through diet, medications, or stress reduction may indirectly support better health outcomes.
  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