Eosinophils % (EOS%)

What is Eosinophils %?

Eosinophils % measures the percentage of eosinophils among your total white blood cells. Eosinophils are white blood cells that primarily fight parasitic infections and play important roles in allergic reactions and asthma. They contain granules filled with proteins that can damage parasites and modulate inflammatory responses.

Why is it Tested?

Doctors order eosinophils % as part of a complete blood count with differential to investigate allergic conditions, parasitic infections, asthma, or certain autoimmune diseases. It’s particularly useful when evaluating unexplained respiratory symptoms, skin reactions, or suspected parasitic infections.

Normal Ranges

Reference ranges vary by lab, but general adult guidelines:

Adults: 1–4%

Normal eosinophil percentages represent a small but important fraction of circulating white blood cells, typically 1-4% in healthy individuals.

Reference ranges vary by authority. Track yours across multiple standards with automatic unit conversions in LabsVault.

What do Abnormal Results Mean?

Abnormal results are not a diagnosis. Always discuss your results with a qualified healthcare provider before making any medical decisions.

Low Eosinophils %

Low eosinophil percentages may occur with:

Acute stress or severe infections
Corticosteroid medications
Cushing’s syndrome
Acute bacterial infections (cells migrate to tissues)

High Eosinophils %

Elevated eosinophil percentages (eosinophilia) commonly indicate:

Allergic conditions (asthma, eczema, food allergies)
Parasitic infections
Certain medications or drug allergies
Autoimmune diseases
Some cancers (Hodgkin lymphoma, leukemia)

How to Track Over Time

Tracking eosinophil percentage trends helps monitor allergic disease progression and treatment response. Seasonal variations may reflect environmental allergies, while persistent elevation warrants investigation for parasitic infections or underlying inflammatory conditions that may require specific treatment.

Eosinophils %