An elevated eos in the blood signifies an increased eosinophil count, according to the American Association for Clinical Chemistry. Eosinophils are a component of the immune system and can be elevated in patients with parasitic infections, fungal diseases, allergies, adrenal illnesses, skin disorders, toxin exposure, autoimmune disease, endocrine disorders and tumors, states Mayo Clinic.
Elevated eosinophils are often an incidental finding in blood tests done for other reasons, notes The Merck Manual Professional Edition. The approach to finding the cause begins by obtaining a thorough clinical history from the patient. It is important to ask about travel history because recent travel can suggest a parasitic infection as the cause of elevated eosinophils. A history of any allergy, drug use and use of herbal products and supplements, as well as any systemic symptoms is also very important information.
The physical exam includes checking the heart, skin, lungs and neurologic signs, explains The Merck Manual Professional Edition. A rash may suggest the presence of an allergic reaction and abnormal lung sounds can indicate asthma. Depending on the findings from the clinical history and physical exam, other tests may be ordered. These include stool and ova for parasites, parasite serology, chest X-rays, urinalysis, liver and kidney function tests and other blood tests aimed at detecting specific diseases.