Methods of Allergy Testing your Doctor might Recommend
If you suspect that you might have an allergy, but you are unsure of the specific allergen that is causing your allergic reaction, your doctor may recommend a variety of allergy testing to diagnose your condition. The different types of allergy testing can be used to identify a variety of allergens. Since some tests will work better than other depending on the type of allergy suspected, it is a good idea to be familiar with the different methods of allergy testing before you make an appointment with your doctor. Tests can fall into three categories: Scratch tests, elimination tests, and blood tests.
The scratch tests are probably the most common type of allergy testing that is done. This test involves placing a small amount of the suspected allergen onto the surface of the skin, and then scratching or pricking the area to allow some of the substance to penetrate the surface. The site is then observed to watch for indication of an allergic reaction such as swelling, redness or itching. A result is often detected in as little as twenty minutes with this method of allergy testing. The other advantage to this type of test is that many different types of allergens can be tested at the same time. This makes this method very useful when the allergen is unknown, for airborne allergens and for allergies from foods and insect bites.
If a food allergy is suspected, another type of allergy testing that is often performed is the elimination diet. In this process, a variety of foods that are potential allergens are eliminated from the diet for a period of several weeks. Each food is then individually introduced back into the person's diet, with careful observation to see which selection will cause the allergy symptoms to return. This method of allergy testing works best on mild allergic reactions, but can be potentially dangerous for severe, anaphylactic allergies. If a severe allergy is suspected, there is a third method of allergy testing that is preferred to ensure that a potentially life-threatening substance is not introduced into the system in any way.
The final type of allergy testing that is commonly performed is called a radioallergosorbent test, or RAST. This test is done in the laboratory, using blood that is drawn from the patient. The blood is examined for the presence of immunoglobulin (IgE) antibodies, since this will indicate whether the immune system is producing an allergic reaction in the body. Elevated levels of these IgE's can tell your doctor whether you are allergic to certain types of allergens, although this type of allergy testing does not tend to be as accurate or precise as other methods.
If your doctor decides that you should have some type of allergy testing done, he will first go through your medical history, and possibly instruct you to stop taking any sort of allergy medication for a period of time prior to the test. This will help to ensure the most accurate results.