Testing for allergy.

1. Mary V. Lasley, MD* 2. Gail G. Shapiro, MD† 1. 2. *Clinical Assistant Professor. 3. 4. †Clinical Professor, University of Washington Medical Center, Northwest Asthma & Allergy Center, Seattle, WA. After completing this article, the reader should be able to: 1. List the indications for immediate-type skin testing. 2. Delineate the populations in which pollen allergy and food allergies are more common. 3. List the most common medicines that can alter the results of allergy skin testing. 4. Explain the commonalities and differences between radioallergosorbent testing and skin testing. 5. Delineate situations in which in vitro testing is indicated. Many children in the United States are affected by atopic disease. It has been estimated that 4% to 6% of children have food allergies, 8% to 10% have asthma, and 15% to 25% have allergic rhinitis. Additionally, large numbers of children who suffer from allergic rhinitis have coexisting otitis media and sinusitis. Further, there is a widespread impression that the incidence of allergic diseases has increased in the past 15 to 20 years, most notably in industrialized countries. The purpose of allergy testing is to help identify potential allergen(s) that are contributing to the allergic disease process. By identifying the allergen, the patient and his or her family can avoid exposures, and the clinician can manage the disease appropriately. Allergy testing can be performed for a variety of foods, aeroallergens, latex, venom, and some medications. Skin testing methods were described initially more than a century ago. In 1873, Charles Blackley performed the first allergy skin tests on patients by scratching the surface of their skin, applying pollen to the scratch, and observing the interaction. In 1908, Mantoux described the intradermal test, which subsequently was used for allergy testing. In the early 1920s, Lewis and Grant described the prick test. The principles of allergy testing described in earlier years remain in practice today, albeit with modifications that include standardized devices and allergen extracts. Skin testing is a major method for identifying allergen-specific immunoglobulin E (IgE). Allergen is …