Skin tests are methods of testing for allergic antibodies when your skin is exposed directly to suspected allergens.
Skin allergy testing is performed to help determine what may be causing your symptoms of an allergic reaction. It is the most common, reliable and relatively painless form of allergy testing. The test is done in the office, and your skin is observed for signs of a local reaction, in response to an allergen. Positive tests indicate the presence of allergic antibodies, however results alone do not diagnose the presence of allergy. Skin tests provide information, which will be interpreted in the context of your medical history and environmental exposure, to understand the cause of your symptoms.
Skin testing is the most sensitive mode of allergy testing, as it evaluates the interaction of a specific allergen with your body's immune components. Skin tests are done in Dr. Schiffman's office.
There are two types of skin tests. Prick or scratch test is minimally invasive. A very small amount of commercial allergen extract or fresh allergen is put into the superficial layer of the skin by making a small indentation or “prick” on the surface of the skin. It is the most common type of skin test. Intradermal testing is slightly more invasive, and involves injecting a small amount of a specific allergen under the skin through a thin needle.
Expectations during a skin test:
A number of different allergens may be tested, including important airborne or environmental allergens, foods, insect venom or drugs. Typical aeroallergens are trees, grasses, weeds, molds, dust mites and animal danders, common in South Florida. It takes about 10 minutes to place the allergens on your skin. They are usually put on the forearm in adults, and the back of young children. Then you will wait 15 to 20 minutes to see if a little swelling appears, where the allergen was placed. It may be red, raised and itchy. The larger the area of swelling, the greater your sensitivity. There may be slight discomfort, but most people tolerate the procedure well. The process may take up to one hour, and reactions gradually resolve within 60 minutes. Occasionally, local swelling at a test site will begin 4 to 8 hours after the skin tests are applied, particularly at sites of intradermal testing. These reactions are not serious and will disappear over the next week or so. They should be measured and reported to your physician at your next visit.
You will be instructed to avoid certain medicines prior to testing, including over the counter medications. Do not take antihistamines for 3 to 7 days before the test. It is okay to continue asthma medications and nasal steroid sprays as these do not interfere with skin tests. Speak with the receptionist, or reference the medication guide before testing, to find out which medications may be continued, and which medications should be held, so they do not affect skin test results.
Very small amounts of allergen are tested on your skin, so skin testing is safe. During the procedure, Dr. Schiffman and her staff will watch for a possible severe allergic reaction, which rarely happens.
Dr. Schiffman will interpret the results in the context of your environmental exposure and medical history. Sensitivity, or positive skin test, does not always equate with allergy, or symptoms with exposure. There may be further challenges, if history fails to support testing results. Your findings will be reviewed, and together, you will create a plan to control your allergies. This means preventing and treating symptoms. This may involve avoiding or limiting contact with your allergens, taking medications to prevent or relieve your symptoms, and starting allergy shots.
Most health insurance plans cover allergy testing and treatment. Please speak with your insurance carrier to verify benefits. You may wish to ask them if you need a referral to see an allergist, your insurance covers special services for your allergies and what allergy testing and medicines are covered under your plan.
A lab test that provides information about an immune component active in allergic reactions
Blood tests are used to identify allergy when skin tests might be unsafe or there is a condition or medication which interferes with skin testing. Serum tests measure specific immunoglobulin E, an antibody produced by the immune system in response to allergen exposure. The amount, or level, of allergen specific IgE in the blood, may be used to follow the evolution of allergy over time. The presence of serum specific antibody determines sensitivity, but does not always equate with allergy.
Immunoglobulin E, or IgE, is a protein which is produced by the immune system in response to specific allergens. When the allergen is reintroduced to the body, IgE play a role in the development of a wide variety of possible allergy symptoms, including nasal congestion, sneezing, hives, itching, swelling, difficulty breathing and others. Blood is drawn by the lab, and typically results are available in less than a week. The measured level of allergen specific IgE is compared to reference values to determine sensitivity.
Dr. Schiffman will interpret the results in the context of your environmental exposure and medical history. There may be further challenges, if history fails to support testing results. Your findings will be reviewed, and together, you will create a plan to control your allergies. This means preventing and treating symptoms. This may involve avoiding or limiting contact with your allergens, taking medications to prevent or relieve your symptoms, and starting allergy shots.
The oral ingestion challenge involves eating a serving of potentially allergic food or drug, in a slow, graded fashion under medical supervision. Typically, it is performed after negative skin or blood testing, or when skin and blood testing has poor predictive power. A graded oral challenge is used for several reasons. It can confirm or disprove a food or drug allergy, when the diagnosis is questionable. It can confirm negative skin testing, and it can determine whether food can be safely re-introduced into the diet of a food or drug allergic child or adult.
The decision to perform an oral food or drug challenge is based on history of reaction and skin and/or blood testing. The child’s age and ability to participate are also considered. During the oral challenge you/your child will be given very small amounts of the specific food/drug being tested. If tolerated, increasing amounts of the challenge item will be given with close observation at each stage. You/your child will be observed for symptoms such as itching, rash, abdominal pain or difficulty breathing, and treated with medications accordingly.