Eosinophils (EO%)

Eosinophil fraction of total white cells.

What it is

Normal eosinophil percentage is 1–4% of total WBC. Elevated percentage may indicate allergy, drug reaction, or parasitic infection.

Why it matters

During chemotherapy, eosinophil trends contribute to the overall picture of how the immune system is behaving and whether drug reactions are developing.

How to test

Full blood count differential.

This information is for educational purposes only. Always discuss testing and interpretation of results with your care team.

Optimal range

1–4% of total WBC.

How often

Each blood count panel.