Do I need a Eosinophils % test?

Do you find yourself dealing with allergies, frequent infections, or unexplained inflammation? Understanding what's happening in your immune system can help you and your healthcare provider make more informed choices about your health.

Eosinophils % measures the proportion of eosinophils among your white blood cells, giving you a snapshot of one aspect of your immune function.

Knowing your eosinophil levels may help reveal whether your immune system is responding appropriately to allergens, infections, or inflammation. This simple marker, included in Listen Health's full immune function panel, empowers you to track patterns over time and work with your healthcare provider to understand what your body is trying to tell you.

Eosinophils % — Key Facts
MeasuresEosinophils typically make up about 1–4% of all white blood cells
CategoryImmune Function
Unit%
Tested inListen Health Standard & Premium membership (100+ biomarkers)
Reviewed byDr Jamie Deans, MBChB

What is it?

Eosinophils are a type of white blood cell found in your blood and tissues. They are part of your immune system and help fight off certain infections, especially parasites, and are involved in allergic reactions.

Eosinophils (%) tells you what percentage of your white blood cells are eosinophils, usually measured as part of a full blood count (FBC). In healthy adults, eosinophils typically make up about 1–4% of all white blood cells, but this can vary depending on age, health, and environment. Eosinophils are produced in the bone marrow and travel through the bloodstream to different tissues, where they help regulate inflammation, tissue repair, and immune responses. They release proteins and chemicals that can destroy invaders like parasites, but can also cause tissue damage if too many are present or if they are overactive.

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Why does it matter?

Eosinophils play a double role in health: they help defend against infections and keep tissues healthy, but can also cause problems if their numbers are too high or too low. High eosinophil percentages (eosinophilia) can be a sign of allergies (like asthma, hay fever, or eczema), certain infections (especially parasites), autoimmune diseases, or rare blood disorders. Chronic high eosinophil levels can lead to tissue damage in organs such as the lungs, skin, gut, or heart, and may require further testing to find the cause. Low eosinophil percentages are less common and usually not a problem, but can occur with some infections, stress, or after taking certain medications

References

  1. Wechsler, M. E., Munitz, A., Ackerman, S. J., et al. (2021). Eosinophils in health and disease: A state-of-the-art review. Mayo Clinic Proceedings, 96(10), 2694–2707. https://doi.org/10.1016/j.mayocp.2021.04.025

  2. Kanda, A., Yasutaka, Y., Van Bui, D., et al. (2020). Multiple biological aspects of eosinophils in host defense, eosinophil-associated diseases, immunoregulation, and homeostasis: Is their role beneficial, detrimental, regulator, or bystander? Biological & Pharmaceutical Bulletin, 43(1), 20–30. https://doi.org/10.1248/bpb.b19-00892

  3. Rodrigo-Muñoz, J. M., Gil-Martínez, M., Sastre, B., & Del Pozo, V. (2021). Emerging evidence for pleiotropism of eosinophils. International Journal of Molecular Sciences, 22(13), 7075. https://doi.org/10.3390/ijms22137075

  4. Jesenak, M., Diamant, Z., Simon, D., et al. (2023). Eosinophils—from cradle to grave: An EAACI task force paper on new molecular insights and clinical functions of eosinophils and the clinical effects of targeted eosinophil depletion. Allergy, 78(12), 3077–3102. https://doi.org/10.1111/all.15884

  5. Thomsen, G. N., Christoffersen, M. N., Lindegaard, H. M., et al. (2023). The multidisciplinary approach to eosinophilia. Frontiers in Oncology, 13, 1193730. https://doi.org/10.3389/fonc.2023.1193730

  6. Kita, H. (2011). Eosinophils: Multifaceted biological properties and roles in health and disease. Immunological Reviews, 242(1), 161–177. https://doi.org/10.1111/j.1600-065X.2011.01026.x

  7. Jackson, D. J., Akuthota, P., & Roufosse, F. (2022). Eosinophils and eosinophilic immune dysfunction in health and disease. European Respiratory Review, 31(163), 210150. https://doi.org/10.1183/16000617.0150-2021

  8. Ramirez, G. A., Yacoub, M. R., Ripa, M., et al. (2018). Eosinophils from physiology to disease: A comprehensive review. BioMed Research International, 2018, 9095275. https://doi.org/10.1155/2018/9095275

  9. Day, K. S., Rempel, L., Rossi, F. M. V., & Theret, M. (2024). Origins and functions of eosinophils in two non-mucosal tissues. Frontiers in Immunology, 15, 1368142. https://doi.org/10.3389/fimmu.2024.1368142

  10. Sturm, E. M., Knuplez, E., & Marsche, G. (2021). Role of short-chain fatty acids and apolipoproteins in the regulation of eosinophilia-associated diseases. International Journal of Molecular Sciences, 22(9), 4377. https://doi.org/10.3390/ijms22094377

  11. Hogan, S. P., Rosenberg, H. F., Moqbel, R., et al. (2008). Eosinophils: Biological properties and role in health and disease. Clinical and Experimental Allergy, 38(5), 709–750. https://doi.org/10.1111/j.1365-2222.2008.02958.x

  12. Liao, W., Long, H., Chang, C. C., & Lu, Q. (2016). The eosinophil in health and disease: From bench to bedside and back. Clinical Reviews in Allergy & Immunology, 50(2), 125–139. https://doi.org/10.1007/s12016-015-8507-6

Frequently Asked Questions

Lymphocytes

Neutrophils %

Monocytes %

Blood Group (ABO) and Rhesus Factor

Mean Corpuscular Volume (MCV)

Red Cell Distribution Width (RDW)

AHPRA Disclaimer: This information is general in nature and should not replace individual medical advice. Always discuss your test results and health concerns with a registered healthcare practitioner.