Eosinophil count (per microliter of whole blood)

What Are Eosinophils?

Eosinophils are a type of white blood cell that helps your body respond to infections and allergic reactions. They are part of your immune system and are usually present in small amounts in healthy blood. When your body detects harmful substances like parasites or allergens, eosinophils increase to help fight them off.

Why Might You Need This Test?

Your doctor may order this test if you have symptoms like persistent itching, skin rashes, asthma, or unexplained allergies. It can also help diagnose conditions such as parasitic infections, certain types of cancer (like leukemia), or autoimmune diseases.

When Might Elevated or Low Eosinophil Counts Occur?

High eosinophil counts may be seen in allergic reactions, parasitic infections, certain lung diseases (like asthma or eosinophilic pneumonia), or some cancers. Low eosinophil counts are less common but can occur with certain blood disorders or immune system conditions.

How Is This Test Performed?

A small amount of blood is drawn from a vein in your arm. The blood sample is then sent to a lab, where it is analyzed to count the number of eosinophils present.