The allergen-specific IgE antibody test is done to screen 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 (instead of other medically supervised allergy testing) when the patient has significant dermatitis or eczema (also a sign of allergies), is taking necessary histamines or anti-depressants that would make other testing more difficult, or if a dangerous allergic reaction could be expected to follow another test.

The allergen-specific IgE antibody test may also be done to monitor immunotherapy or to see if a child has outgrown an allergy, although it can only be used in a general way; the level of IgE present does not correlate to the severity of an allergic reaction, and someone who has outgrown an allergy may have a positive IgE for many years afterward.

The allergen-specific IgE antibody test is usually ordered when you have signs or symptoms that suggest that you have an allergy to one or more substances.

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 and 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 usually indicate an allergy, but even if your specific IgE test was positive, you may or may not ever have an actual physical allergic reaction when exposed to that substance. And the amount of specific IgE present does not necessarily predict the potential severity of a reaction. 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 complete blood count (CBC) 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.