The allergen-specific IgE antibody test is done to test for an allergy (a type I hypersensitivity) to a specific substance or substances when a patient presents with acute or chronic allergy-like symptoms.
The allergen-specific IgE antibody test may be done when skin prick tests are not possible. If the patient has significant dermatitis or eczema or is taking anti-histamines, skin prick tests are difficult to perform and/or interpret.
The allergen-specific IgE antibody test has limited use in checking whether a patient has outgrown an allergy as the test may remain positive even in someone who has long outgrown their allergy. The usefulness of allergen-specific IgE to monitor response to immunotherapy is unclear, and may remain positive even after successful immunotherapy.
Normal negative results indicate that you probably do not have a "true allergy", an IgE-mediated response to that specific allergen, but the results of allergen-specific IgE antibody tests must always be interpreted and used with caution on the advice of your doctor. Even if your IgE test is negative, there is still a small chance that you do have an allergy.
Elevated results often indicate an allergy. However, not all patients with a positive specific IgE test will have an actual physical allergic reaction when exposed to that substance – the patient in this case is said to be “sensitised” rather than allergic to the substance. The amount of specific IgE present does not necessarily predict the severity of a reaction, although the higher the level the more likely the patient is to have a reaction of some sort to the allergen. Your clinical history and other allergy tests, done under close medical supervision, may be necessary to confirm an allergy diagnosis.
Sometimes your doctor will look at other blood tests for an indirect indication of an ongoing allergic process, including your total IgE level or your full blood count (FBC) and white blood cell differential (specifically at your eosinophils and basophils). Elevations in these tests may suggest an allergy, but they may also be elevated for other reasons.
This article was last reviewed on 24 May 2007. | This article was last modified on 19 October 2011.
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