Eosinophils
Eosinophils are white blood cells that release granules containing enzymes to target parasites and regulate allergic and asthmatic inflammation. Elevated counts are typical in allergies, asthma, eczema, drug reactions, parasitic infections, and some cancers and autoimmune conditions. Very high counts warrant evaluation for hypereosinophilic syndromes.
Optimal range: who says what
No institution or named practitioner we track states an optimal target for Eosinophils. How we verify ranges.
- General guidance, no named sourceWithin referenceNo separate optimal established. Persistent elevation usually tracks allergy, asthma, or parasitic exposure
- Published reference interval1-4%Medscape
- Lab reference interval1-4% or 0.04-0.4 x10^9/LWhat a lab report flags against. A lab interval is not an optimal target.
20 of 21 itemized panels
Complete Blood Count (CBC)
Why Eosinophils matters
Elevated in allergies, asthma, parasitic infections, and some cancers. Important for diagnosing allergic conditions and monitoring treatment response.
Reading a Eosinophils result
The absolute eosinophil count (AEC) is the eosinophil percentage multiplied by the WBC count. MedlinePlus gives a normal AEC below 500/µL; ARUP uses 50 to 500/µL (1 to 6% of white cells). ARUP calls >500 to 1,500/µL eosinophilia, and >1,500/µL on two counts at least 4 weeks apart hypereosinophilia. The WHO grades it mild up to 1,500, moderate 1,500 to 5,000, and severe above 5,000/µL.
Common causes of a high result
- Allergic disease, including hay fever, and eczema
- Asthma
- Parasitic infection, such as worms
- Fungal infections
- Medicines, including some antibiotics, psyllium laxatives, amphetamines and interferon
- Adrenal insufficiency, autoimmune disease, or blood cancers such as leukemia and lymphoma
Common causes of a low result
- Corticosteroid medicines
- The body overproducing cortisol
- Alcohol intoxication
Caveat: The count cannot tell an allergy from a parasite infection; the history and follow-up tests do that (MedlinePlus).
What to check next
- A repeat CBC for counts of 500 to 1,500/µL; ARUP says a repeat may not be needed above 1,500/µL, especially with symptoms
- Strongyloides IgG antibody testing before any glucocorticoid treatment (ARUP)
- A smear review and, only after secondary causes are ruled out, a bone marrow workup (ARUP)
Sources: MedlinePlus: Eosinophil count, absolute; MedlinePlus: Blood differential test; ARUP Consult: Eosinophil-related disorders. Checked against these sources 2026-09-23. General information, not medical advice; your lab's reference interval and your clinician's reading take precedence.
Which Providers Test Eosinophils?
Cheapest: Oura Health Panels at $99/year. Most comprehensive: Function Health, 160+ biomarkers for $365/year.
20 panels that include it, cheapest first
| Provider | Annual Cost | Total Biomarkers | $/Biomarker |
|---|---|---|---|
| $99 | 50 | $1.98 | |
| $190 | 100+ | $1.90 | |
| $250 | 65 | $3.85 | |
| $297 | 100+ | $2.97 | |
 Labcorp OnDemand | $338 | 50+ | $6.76 |
 Superpower | $349 | 100+ | $3.49 |
| $349 | 75+ | $4.65 | |
 WHOOP Advanced Labs | $349 | 65 | $5.37 |
 Function Health | $365 | 160+ | $2.28 |
| $365 | 100+ | $3.65 | |
| $375 | 108 | $3.47 | |
| $449 | 83 | $5.41 | |
| $495 | 80+ | $6.19 | |
| $499 | 100+ | $4.99 | |
| $700 | 138 | $5.07 | |
| $829 | 54 | $15.35 | |
| $895 | 100+ | $8.95 | |
| $1188 | 70+ | $16.97 | |
| $1198 | 40+ | $29.95 | |
| $1950 | 130+ | $15.00 |
$/Biomarker is annual cost divided by the panel's advertised biomarker count, not the price of this one test. We track 23 blood test providers (32 plans); 21 of those plans are itemized marker by marker. Compare all of them.
1 itemized panel does not include Eosinophils
11 providers not itemized in our matrix
We have not itemized these marker by marker (some sell tests one at a time), so this page cannot say whether they offer Eosinophils. Check with them directly.
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Frequently Asked Questions
What is the optimal range for Eosinophils?
No institution or named practitioner we track states an optimal target for Eosinophils. General guidance without a named source: Within reference (No separate optimal established). Published reference intervals: 1-4% (Medscape). Lab reference interval: 1-4% or 0.04-0.4 x10^9/L. That is what a lab report flags against, not an optimal target.
Which blood test providers include Eosinophils?
20 of the 21 blood testing panels we itemize marker by marker include Eosinophils in their panels. This biomarker is widely available across major providers.
Medical Disclaimer
This information is for educational purposes only and is not medical advice. Always consult with a qualified healthcare provider about your specific health needs.
Last reviewed Sep 23, 2026 · First published Nov 30, 2025