Eosinophils
Disclaimer: Information on this page is for educational purposes. Consult a physician to interpret your test results. Health Vault helps track biomarker trends but does not replace medical advice.
What This Test Measures
Eosinophils participate in allergic reactions and defense against parasites. They release mediators that drive inflammation in allergy and asthma.
Eosinophilia (>0.5 × 10⁹/L or >4–5%) occurs in allergic rhinitis, asthma, parasitic infections, drug reactions, and hypereosinophilic syndromes.
Marked eosinophilia (>1.5 × 10⁹/L) requires evaluation for parasitic infections, malignancy, and endocrine disorders.
Normal Ranges
| Group | Reference Range |
|---|---|
| Men | 1–4% (<0.5 × 10⁹/L) |
| Women | 1–4% (<0.5 × 10⁹/L) |
| Children | 1–6% |
Reference ranges may vary by laboratory and assay method.
Causes of High Levels
- Allergic diseases (asthma, eczema, rhinitis)
- Parasitic infections (ascariasis, toxocariasis)
- Drug hypersensitivity
- Eosinophilic esophagitis
- Hypereosinophilic syndrome
Causes of Low Levels
- Acute stress, corticosteroids
- Cushing syndrome
- Hyperadrenalism
- Eosinopenia is rarely clinically significant
Test Preparation
- No preparation required
- Report allergies and travel history (parasites)
Related Biomarkers
| Biomarker | Relationship |
|---|---|
| White Blood Cells | Total leukocyte count |
| Basophils | Other granulocytes in allergy |
| C-Reactive Protein (CRP) | Rule out infectious inflammation |
FAQ
How often should I take this test?
With allergy and asthma — during flares; with CBC — annually.
What should I do if my result is abnormal?
Eosinophilia >1.5 × 10⁹/L warrants parasite, allergen, and hematologic evaluation.
Last updated: June 2026