Overview

Eight foods cause 90 percent of all food allergies. These are eggs, milk, nuts, peanuts, fish, shellfish, soybeans, and wheat. It’s possible to be allergic to more than one food and have a severe reaction to the smell alone. Food allergies can develop for the first time at any age and can be mistaken for food intolerance.

Allergies often develop in childhood. Some people grow out of their allergies. But many do not. There are also those who experience more severe reaction over time. Food allergies can cause painful and sometimes life-threatening reactions if not handled properly.
 

Immunoglobulin E (IgE) is a class of antibody (immune protein) associated with allergic reactions. It is normally found in very small amounts in the blood. This test measures the amount of allergen-specific IgE in the blood in order to detect an allergy to a particular substance.

 

IgE is an antibody that functions as part of the body's immune system, its defense against "intruders." When someone with a predisposition to allergies is exposed to a potential allergen such as food, grass, or animal dander for the first time, that person becomes sensitized. The person's body perceives the potential allergen as a foreign substance and produces a specific IgE antibody that binds to specialized mast cells in the skin, respiratory system, and gastrointestinal tract, as well as to basophils (a type of white blood cell) in the bloodstream.

 

With the next exposure, these attached IgE antibodies recognize the allergen and cause the mast and basophil cells to release histamine and other chemicals, resulting in an allergic reaction that begins at the exposure site.A total IgE test measures the overall number of IgE antibodies in the blood, while a specific IgE test measures for a response to individual allergens.

 

Each allergen-specific IgE antibody test performed is separate and very specific; for example, it will test honeybee versus bumblebee, egg white versus egg yolk, and giant ragweed versus western ragweed.