What is Eosinophilia? Simple Answers to Basic Questions

Eosinophilia is the medical term that describes an abnormally high eosinophil count, i.e. too many eosinophils in the bloodstream and certain tissues. The term eosinophilia derives from the Greek words eosinophil (= eosin-loving cell) and philia (= love of, tendency to, excessive number of).

2) What are eosinophils?

Eosinophils (a.k.a. acidophils) are a type of white blood cells (leukocytes). They are part of the body's immune system, i.e. the defense mechanism against parasitic, bacterial, and viral infections. Eosinophils are granulocytes, which means that their cytoplasm contains large granules. These granules turn bright red when exposed to a certain acidic stain called eosin (hence the name "eosinophils" to describe this particular type of white blood cells.)

3) Where are eosinophils produced?

Eosinophils (as well as red blood cells and platelets) are produced in the bone marrow.

4) What is a normal eosinophil count?

A normal eosinophil count is generally no higher than 350 eosinophils per microL of whole blood.

5) What is a high eosinophil count?

An eosinophil count over 400-450 per microL of whole blood is considered high. In severe forms of eosinophilia, the number of eosinophils can be as high as 5,000 cells.

6) What causes eosinophilia?

The exact causative mechanisms of eosinophilia remain largely unclear. Many cases of eosinophilia are termed "idiopathic", which means "of unknown origin". A wide range of conditions, ranging from asthma and hay fever to parasitic infections, autoimmune diseases, and certain forms of cancer, have been known to trigger an abnormally high amount of eosinophils.

7) What are the symptoms of eosinophilia?

The symptoms of eosinophilia are essentially those of the underlying condition that triggers it. For instance, if the underlying condition is asthma, then symptoms include wheezing, dyspnea (difficulty breathing), and breathlessness. If, on the other hand, the triggering factor is a parasitic infection, predominant symptoms will probably be skin rashes, abdominal pain, and fever.

8) How is eosinophilia diagnosed?

An eosinophil count test is performed as part of a CBC (complete blood count). If eosinophilia is suspected or detected, further testing may include tissue biopsies, CT scans, X-rays, liver function tests, serological exams, stool analysis, and urinalysis.

9) How is eosinophilia treated?

The treatment for eosinophilia targets the underlying condition, whether this is a seasonal pollen allergy or a malignancy. Corticosteroid treatments have been generally successful in treating certain forms of eosinophilia, especially if the underlying condition is not malignant. In severe forms of eosinophilia, where vital organs (e.g. the heart and lungs) are affected, more aggressive drug regimes are used, including chemotherapeutic agents and anticoagulant therapy. Surgery may be necessary to restore the function of affected organs.

Sources:

http://www.emedicine.com/med/topic685.htm

http://www.merck.com/mmpe/sec11/ch139/ch139b.html