Eosinophils are a type of white blood cell known as granulocytes. An eosinophil plays an important part in immune response within the body and changes in eosinophil blood cell count may be noted with certain allergic conditions and infections.
Peripheral Blood Eosinophil Count Values or Readings
Any abnormality in eosinophil count is usually detected on a complete blood count (CBC) or full blood count (FBC) test. In most blood work, eosinophil count is expressed as the number of cells per cubic microliter. (µL) Alternatively, the eosinophil count may be recorded as a percentage of total white blood cell (leukocyte) count, along with other white blood cells like monocytes, basophils, neturophils or lymphocytes.
Eosinphils are present in bone marrow and other tissues in the body but the measurement in a blood test is only of those eosinophils circulating in the blood, also known as the peripheral blood eosinophil. This blood eosinophil count does not indicate the eosinphils in the bone marrow or blood tissue. Normal values for peripheral blood eosinophil count is usually less than 350/µL. Any value above 350/µL is known as eosinophilia. In extreme cases, a blood eosinophil count greater than 1,500/µL may be recorded and this is known as hypereosinophilia. Eosinophilia or hypereosinophilia should only be conclusively diagnosed when considering the percentage to other white blood cells.
Common Causes of Eosinophilia or Hypereosinophilia
- Allergic conditions, like asthma, atopic Dermatitis (eczema), allergic rhinitis (hay fever).
- Certain food allergies, like milk allergies (not food intolerance).
- Infections, human intestinal parasites, invasive fungal infections like Pneumocystic carinii infection (HIV/AIDS)
- Most lung pathologies.
- Cancer, carcinomas and sarcomas
- Immunodeficiency syndromes
- Connective tissue disorders, like Crohn’s disease, sarcoidosis.
- Autoimmune disorders like psoriasis, SLE.
A raised eosinophil count is not a diagnosis for a specific medical condition or disease without considering other factors like signs or symptoms, case history and findings upon physical examination as well as other diagnostic investigation. It is important to consult with your medical doctor about your blood test values as any blood work is only an investigative technique.
Article reviewed by Dr. Greg. Last updated on September 2, 2009