Total IgE measures blood levels of antibodies produced by your immune system in response to allergens.
Immunoglobulin E (IgE) is an antibody that initiates an allergic reaction. When you are exposed to an allergen—a normally non-harmful substance that the immune system assumes is dangerous, like peanuts—your body makes specific IgE antibodies designed to recognize that allergen in the future. Then, when you are re-exposed to the same allergen, your immune system quickly produces a large amount of allergen-specific IgE particles to identify and eliminate the allergen.
The total IgE test detects the presence of IgE antibodies in your blood, indicating an increased likelihood that you will experience allergic reactions. Tests for allergen-specific IgE particles are then used to provide information about the specific substances causing your allergic reactions.
Allergic reactions can range from localized patches of red, itchy skin to anaphylaxis, which involves a sudden drop in blood pressure and difficulty breathing. Allergic reactions can vary widely in both type and severity depending on the person and allergy. The following symptoms are strong indications that you should measure your IgE levels:
Unlike an IgG test (known as a food sensitivity test), which only measures the common antibody immunoglobulin G and doesn't accurately predict specific food allergies, an IgE test focuses on the class of antibody that's directly associated with allergic reactions — giving you much more specific results when it comes to identifying allergic triggers.
Your IgE test results are reported in fluorescent standard units (FSU). A reading lower than 0.01 FSU indicates no detectable IgE. Generally, the higher the level of IgE, the greater the risk that you will experience allergic symptoms. Each potential allergen is in a class based on this level, as below.
While the higher the IgE level, the greater the likelihood you will have allergic symptoms for a particular allergen, even allergens that fall into the lower Classes should be monitored. They can contribute to the cumulative allergen burden, for example during allergy season.
If you have elevated IgE levels for any indoor, outdoor, or food allergies, a board-certified allergist can work with you to create a program that helps to alleviate symptoms. This can include the use of antihistamine and other medications, allergen avoidance and immunotherapy.
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