Allergy Diagnostic Testing
Identifying the offending allergen(s) by allergy testing is the first step to determining the most appropriate course of therapy.
At the present time, there are two primary ways to test for allergies: skin tests and blood tests. Our practice uses a combination of these tests. An individualized evaluation will be done at the time of your visit to determine which test will be best for you.
Allergy Skin Tests:
Allergy skin testing is easily and painlessly performed on the skin of the forearms. The testing consists of gentle pricks made with disposable plastic prongs with drops of allergen extract on them. This completely sterile and disposable applicator tests for dust mites, molds, animal dander and pollens.
If you are allergic, a slight swelling, itching and reddening of the skin will occur. Our staff will record the severity of the reaction. The size may vary from allergen to allergen depending on your level of sensitization to each. For example, you may be highly allergic to grass pollen but only mildly allergic to oak tree pollen. The size of the reaction is then compared to the positive and negative "controls" or base line. The information from the skin testing can determine in minutes what you are allergic to with an incredible degree of accuracy, helping your doctor to determine the cause of your allergies. The allergic reaction from skin testing will generally subside after a short period of time.
Allergy Blood Tests:
Blood testing for allergies is a newer technology for allergy diagnosis. These measure the same allergy triggers as skin tests and are useful in certain patients such as young children, and those who are on certain medications that prevent us from doing skin tests. On occasion it may be appropriate or necessary to do blood testing in addition to skin testing in order to identify the causative allergens.
Blood tests identify allergen specific IgE antibodies, which are formed to the specific allergens to which an allergic individual is sensitized. It is a laboratory test that measures the true quantitative level of allergen specific IgE, and is used to add objective evidence in diagnosing patients with allergy-like symptoms. These tests, like skin tests, provide a clinically relevant means of confirming or excluding the presence of allergic disease in patients.
This specific IgE blood test was formerly called the RAST test, but over the last twenty years since its inception, many technological advances have made that original test obsolete. Newer more advanced, accurate and sensitive tests have replaced the RAST test, yet the name “RAST Test” has stuck in the day to day use of the test (much like the term “Xeroxing” for photocopying)
The ImmunoCAP™ has also been accepted by the FDA as a truly quantitative measure of IgE. In recent studies it was shown to be the only specific IgE blood test to perform accurately and reliably across the entire clinical range and provides accurate, quantitative IgE results. This test is endorsed by the National Institutes of Health (NIH) and other health organizations such as the America Academy of Allergy, Asthma and Immunology and America College of Allergy, Asthma and Immunology. Leading institutions such as Johns Hopkins, the Mayo Clinic and the Cleveland Clinic use ImmunoCAP™ for their patients.
ImmunoCAP Rapid™. The Allergy Center will also be one of the first clinics in the US to employ this new finger stick test. It is a semi-quantitative test measuring specific IgE antibodies to ten common allergens in only 20 minutes. Since the test only requires a small amount of blood from a finger stick, it is an ideal test for screening young infants for inhalant allergy. If additional allergen testing is required, skin tests or the original ImmunoCAP™ blood tests are then recommended.