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If you or your doctor suspects you have a peanut allergy, you should make an appointment with an allergist or immunologist right away. This professional will first obtain a thorough history and physical. The focus of this appointment will be the response you experience when you encounter peanuts or tree nuts. Accommodating food allergies can have a profound effect on lifestyle, quality of life and mental health. It is important to be prepared for a possible allergic reaction, but to also not live in fear based only on tests which may have false positive results. Ask about possible desensitization treatments called Immunotherapy to reduce the risk of a severe reaction from a small accidental exposure. There are several different Immunotherapy protocols, some of which are still in clinical trials. There are several immunologic tests that can be administered to provoke the IgE response. This response will help assess the scope of the peanut allergy, but ultimately the only way to be absolutely certain is with an Oral Challenge test. If the patient has had anaphylaxis previously the doctor may choose to start with blood testing to avoid the risk of triggering that reaction again. Typically skin prick testing is the first to be performed. This test involves exposing you to a potential allergen. The possibility exists that you may experience anaphylaxis. Therefore, this test is done under close supervision of a skilled allergist and immunologist who are also skilled at treating anaphylaxis. The allergist will perform an initial diagnostic, exposing you to common allergens. A small amount of calibrated solution will be placed on the skin and a special tool will painlessly make a shallow scratch. The allergist will diagram the scratch sites, to keep track of which area is injected with which allergen. You will be monitored for any acute and dangerous response that requires immediate attention. Otherwise, the injection sites are checked for the presence of a "wheal," or raised itchy area, which would indicate an allergy. The allergist will draw blood to be used for IgE response testing. This type of test has the benefit of causing no potential risk to the patient, as the patient is not exposed to the potential allergen. Blood testing tends to have some false positive results. Ask if newer RAST or ImmunoCap blood testing for Peanut is available. The ImmunoCap test is a second generation RAST test that measures a person's IgE levels to an allergen. These tests may not yet be covered by your medical insurance. Ask if you can pay out of pocket if you are interested or if your health clinic will not perform the test ask where else you can go to get tested. The peanut protein is presented in the laboratory with the patient's blood sample. Radio labeled human IgE human antibody is added and the antibodies will combine to the allergen. RAST testing is ranked on 0-6 scale. With zero indicating no sensitivity and six is highest sensitivity. A RAST of 3 or less requires more specific testing such as an oral challenge to confirm the allergy. It is important to ask about the rate of false positive results during basic blood or skin prick testing. This is the only way to be absolutely certain an allergy does not exist. Since most Peanut allergies are severe with a high risk of anaphylaxis this testing should only be done in a supervised medical environment that can provide emergency treatment if required. You will start with small doses of the allergen, starting with exposure to only the lips before swallowing. After each dose there is a waiting period, then the next dose is increased until a certain threshold is reached or until a reaction occurs. After the last dose you will need to wait four hours to ensure there is not reaction before you are released. This test, called DBPCFC for short, is used to confirm a specific allergy. This is also the testing used to determine eligibility to participate in clinical trials. This test is costly and time-consuming. The patient will need to go through two oral food challenges that are at least one week apart. In one challenge the patient is given allergen and in the other a placebo. Neither the patient nor the allergist knows which capsule has the allergen, which helps to eliminate the potential for false reactions. It can be useful for avoiding unnecessary elimination diets by pinpointing the exact allergen that affects a person.
Visit an allergist or immunologist. Go through allergy testing. Take a skin prick test. Take a blood test. Take an oral challenge. Use the double-blind placebo-controlled food challenge as a last resort.