The allergen-specific IgE antibody test is a blood test used to screen for an allergy to a specific substance or substances. This is especially true if symptoms are recurrent and appear to be tied to triggers such as exposures to particular foods or environment. It is also helpful in diagnosis when other family members are known to have allergies.
Various allergy tests are performed by exposing a person to different substances under careful medical supervision. The usefulness of these tests, however, can be affected by skin conditions and by medications (such as histamines and anti-depressants). With some tests there is also the potential for severe reactions that may be life threatening. In these cases, the allergen-specific IgE antibody test may be ordered as an alternative, as it is performed on a blood sample and does not have an effect on the person being tested.
The allergen-specific IgE antibody test may also be done to monitor immunotherapy (desensitization) or to see if a child has outgrown an allergy. It can only be used in a general way, however, as the level of IgE present does not correlate to the severity of an allergic reaction. Someone who has outgrown an allergy may have a positive IgE for many years afterward without allergy symptoms present.