Eosinophils
A small subset of white blood cells involved in allergy and in fighting parasites. A raised eosinophil count characteristically points to allergic conditions (asthma, hay fever, eczema, drug reactions) or, worldwide, parasitic infection.
What it measures
Eosinophils are a minority white cell with two main jobs: driving allergic and asthmatic inflammation, and defending against parasitic worms. They normally make up only a small fraction of white cells, so the meaningful finding is a raised count (eosinophilia). The classic associations are allergic — asthma, hay fever (allergic rhinitis), eczema, and drug reactions — and, especially in or after travel to endemic areas, parasitic infection. Less commonly, a high eosinophil count can reflect certain autoimmune and inflammatory diseases, some skin conditions, adrenal insufficiency, or, when very high and persistent, a rare blood disorder. A low eosinophil count has little clinical significance on its own. The count is read within the full blood count differential and interpreted with the person's allergy history, medications and travel.
What a high value can mean
- Allergic conditions — asthma, hay fever (allergic rhinitis), eczema, food and drug allergy.
- Drug reactions — a recognised and important cause.
- Parasitic (worm) infection — a leading cause worldwide, especially with relevant travel.
- Certain skin conditions.
- Autoimmune and inflammatory diseases; adrenal insufficiency.
- Rarely — a very high, persistent count from a blood disorder (hypereosinophilic syndrome) or some cancers.
What a low value can mean
- Little clinical significance — a low eosinophil count is common (e.g. with acute infection or steroids) and not usually a concern.
When to discuss with a doctor
A mildly raised eosinophil count in someone with known allergies or asthma usually fits the picture and needs no special action. A more marked or unexplained eosinophilia deserves a look for the cause, guided by the story: a medication review (drug reactions are common), an allergy and asthma assessment, and, with relevant travel or symptoms, testing for parasites. A very high, persistent eosinophil count, or one with damage to organs such as the heart or lungs, needs specialist assessment. Mediora.AI shows the eosinophil count within the white-cell differential, flagging a raised value that fits an allergic or parasitic pattern; the interpretation belongs with your doctor.