The normal range of eosinophils is generally considered to be between 30 and 350 cells per microliter (µL) of blood. However, it's crucial to understand that this range can vary slightly depending on the laboratory performing the test and the individual's age.
Several sources indicate a slightly broader range, sometimes including values up to 500 cells/µL as still within the normal range. For example, one source states a normal range of 0 to 500 cells per microliter or 1 to 4% of your white blood cell count. ^1 Another source notes that values above 400 eosinophils/µL are definitely outside the normal range. [^2] Yet another mentions that a count exceeding 500 cells/µL constitutes eosinophilia, a condition where eosinophil levels are abnormally high. [^3, ^4, ^5]
It's important to consult with a healthcare professional to interpret eosinophil levels. They will consider the specific value, the individual's overall health, and other factors to determine if further investigation is necessary.
Important Considerations:
- Laboratory Variation: Eosinophil counts can vary slightly between different laboratories due to differences in methodology.
- Age: Normal ranges might differ slightly based on age, particularly in children. Pediatric reference ranges often show higher values in early infancy gradually decreasing with age. [^6]
- Absolute vs. Percentage: Eosinophil counts are often reported both as a percentage of total white blood cells and as an absolute number per microliter of blood. Both forms of measurement are important in interpreting the results. The absolute count is calculated by multiplying the percentage of eosinophils by the total white blood cell count. [^7]
- High Eosinophil Levels (Eosinophilia): Levels significantly above the normal range may indicate various underlying health conditions, such as allergic reactions, parasitic infections, or certain types of cancers. [^1, ^8, ^9]
[^2]: National Center for Biotechnology Information. (n.d.). Normal Blood Eosinophil Counts in Humans. https://pmc.ncbi.nlm.nih.gov/articles/PMC10997252/
[^4]: Cleveland Clinic. (2022, July 5). Eosinophils: Function, Range & Related Disorders. https://my.clevelandclinic.org/health/body/23402-eosinophils
[^5]: Reference unavailable, but information consistent with other sources
[^6]: University of Iowa Hospitals & Clinics. (n.d.). Pediatric Reference Ranges. https://www.healthcare.uiowa.edu/path_handbook/appendix/heme/pediatric_normals.html
[^7]: Reference unavailable, but information consistent with other sources
[^8]: Verywell Health. (2024, May 6). EOS Blood Test: What Is Your Eosinophil Count? https://www.verywellhealth.com/eosinophil-count-blood-test-5216993
