According to Mayo Clinic, elevated eosinophils could mean the body is attacking a substance it has deemed foreign, such as a parasite or allergen. Mayo Clinic lists potential causes of eosinophilia, the term for eosinophil counts elevated above 500 per microliter, as fungal diseases, adrenal conditions, skin disorders, toxins, autoimmune diseases, endocrine disorders and tumors.
According to MedlinePlus, some medications can cause elevated eosinophils, including some antibiotics, interferon, tranquilizers, acetaminophen and laxatives containing psyllium. MedlinePlus and Mayo Clinic both link eosinophil overproduction to asthma and hay fever.
Eosinophils are a type of white blood cell that create an inflammation in the body, says Healthline, Inflammation is both good and bad in that it traps infections but can cause tissue damage. Leukemia, ulcerative colitis, scarlet fever, lupus and Crohn’s disease are other potential diseases that can cause a high eosinophil count.
Eosinophils are measured as a part of a regular blood panel. The normal eosinophil range in blood is about 350 per microliter, says Healthline. Mayo Clinic explains that eosinophilia may also be detected in tissue samples or samples of certain fluids, such as mucus, at the site of an inflammation or infection. Tissue eosinophilia and blood eosinophilia are not necessarily present at the same time.