Another useful tool in diagnosing and managing allergies is blood testing, called allergen-specific IgE testing. This test measures the level of antibody produced in the blood in response to an allergen. The level of specific IgE to an allergen in the blood (previously known as RAST testing) does not describe the severity of the reaction.
This is a useful tool your allergist may use to measure trends in blood work, in addition to skin testing and reaction history. IgE blood tests are often used when skin tests may be unsafe or children have a skin condition that may interfere with skin testing.