Allergies occur when the immune system overreacts to substances that enter or come into contact with the body. When this happens, the body releases immunoglobulin IgE antibodies and other proteins and chemicals that cause the tell-tale symptoms of allergies---hives, runny nose, itching, swelling, wheezing and, in severe cases, anaphylactic shock. Allergy tests can help identify the specific substances to which a person is allergic. Proper diagnosis of the specific allergens helps manage and treat the symptoms and underlying causes. Allergy tests are highly effective and safe for both children and adults.
Skin Test
In a skin test, the allergist drops a small amount of suspected allergen onto the skin, usually, the patient's forearm. He pricks the area with a small needle so the allergen gets under the skin. Development of a red, itchy wheal on the site within 15 minutes of pricking indicates a positive allergic response. Skin testing is the most common type of allergy testing as it is painless and provides results rapidly. A common side effect of a skin test is itchy bumps or hives around the wheal. The skin test can result in anaphylactic shock in cases of severe allergies, so it is important to conduct the test in an appropriate allergy clinic.
RAST Blood Test
RAST, short for radioallergosorbent test, measures the level of specific IgE antibody present in a patient's blood. The patient needs to give a certain amount of blood at the clinic or laboratory. A laboratory technician will add the suspect allergen, attached to a detector enzyme, to the patient's blood. If the patient is allergic to the suspect allergen, specific IgE antibodies will bind to the allergen-enzyme molecules. A detection method measures how much bound allergen-IgE-enzymes are in the blood, thus determining the sensitivity to that particular allergy. Common side-effects are related to giving blood, such as pain and slight bruising. It may take a few weeks before RAST test results become available.
Elimination Test
An elimination diet can identify a person's sensitivity to specific food. The patient eats a diet without the suspect food for four to seven days, and keeps removing new food until all the symptoms of allergies subside. Once clear, the patient reintroduces foods to his diet, one at a time, until symptoms reappear. An elimination diet may be best for people with multiple food allergies. This diet, however, may not identify food allergens that are hidden in packaged or processed food.
