Can this result diagnose a condition on its own?

No. A laboratory result should be interpreted with related tests, symptoms, medical history, and the reference information on the report.

Which reference range should I use?

Use the reference interval provided by the laboratory that performed the test. Clinical decision cutoffs, when relevant, are shown separately.

When should I discuss the result with a healthcare professional?

Professional assessment is appropriate when a result is markedly outside the reference interval, serious symptoms are present, an abnormality persists or recurs, or follow-up has been recommended.

Information about a laboratory test

Eosinophils: What Does This Blood Test Measure?

Shows the percentage or absolute number of eosinophils, white blood cells involved in responses to parasites and in allergic or inflammatory reactions.

Test summary

Test name: Eosinophils
Abbreviations: EOS
Category: Hematology / Immunology
Panel: WBC Differential / Hemogram
Specimen: Whole blood
Common units: %, /µL, x10^9/L

What does the test measure?

Shows the percentage or absolute number of eosinophils, white blood cells involved in responses to parasites and in allergic or inflammatory reactions.

Why is the test ordered?

May be used when evaluating allergic disease, parasitic infection, and some inflammatory or hematologic conditions.

Information about a low result

A low eosinophil result is usually not an important finding by itself.

Information about a high result

A high eosinophil result may be associated with allergic conditions, some parasitic infections, and other inflammatory or hematologic causes.

Reference and clinical context

Use the reference interval printed on your own laboratory report first. Reference intervals may vary by laboratory, method, unit, age, sex, pregnancy, specimen, and other conditions. Numeric records in this workbook are explicitly labeled as either source-based example reference intervals or clinical decision cutoffs.

Reference range 1

>= 1 – <= 4 %

Population: General
Specimen: Whole blood

Example differential percentage

MedlinePlus example differential percentage; absolute counts and lab-specific ranges may be more relevant.

Reference ranges may vary by laboratory, method used, age, sex, pregnancy status, and clinical context. The reference range on your own laboratory report takes precedence.

Interpretation notes

The result does not identify the cause by itself and should be interpreted with symptoms and the other white-cell values.

Related specialties

Allergy and Immunology
Internal Medicine
Infectious Diseases
Hematology

Frequently asked questions

Sources

Blood Differential — U.S. National Library of Medicine (MedlinePlus)
Government medical reference · 2024 · Neutrophil, lymphocyte, monocyte, eosinophil, basophil roles and example percentages · Verified: Aug 11, 2026