What is a RAST test ?
A RAST test is a simple blood test performed to help identify the source of an allergy. While the name is an acronym for radioallergosorbent, the RAST test is also sometimes referred to as an allergen-specific IgE antibody test. Generally, this type of test is used when a food allergy is suspected, as evidenced by the appearance of a skin rash or eczema. It may also serve as a precursor to more specific blood tests if a chronic allergic response is indicated, such as a white blood cell differential count, eosinophil count, or basophil count. The RAST test is also the standard alternative to introducing a suspected allergen directly to the patient via a skin prick test, which may cause a serious reaction. The mechanism behind the RAST test is fairly simple. First, the test is designed to detect the presence of immunoglobulin E (IgE), a class of antibodies produced by the immune system to bind with the invading allergen and trigger the release of the inflammatory mediator, histamine. Whi
A RAST (radioallergosorbent test) involves drawing blood. Blood is drawn from a vein and then sent for testing for the presence of allergen-specific antibodies. A RAST test can be done when a skin test can’t be done or wouldn’t be safe. Both tests are highly specific, but the skin test is cheaper, more sensitive and produces immediate results. If I test positive for allergies, how will my condition be treated? There are several ways to treat allergies. Antihistamines are often prescribed to relieve allergy symptoms. Decongestants may help relieve nasal congestion and are often prescribed along with antihistamines. Nasally inhaled corticosteroids that work by reducing the swelling in the membranes of the nose and sinuses are another option. Allergy shots (desensitization) involve getting injections of small amounts of the triggering allergen. This is similar to vaccinations or immunizations. That is, your body will react to the injected allergen by building immunity to it. Subsequent en
A RAST (RadioAllergoSorbent Test) is a blood test done to look for allergies. This is a way to look for Immunoglobulin E (IgE), the allergic antibody. IgE is a protein in our body that attaches to food proteins to start an allergic reaction. In order to have an allergic reaction, you need to have IgE to the food in question. A RAST test looks for IgE in your blood. This test cant tell you if you will react or how severely you will react, but tells you that you have IgE against the food. What is a CAP-RAST test? A CAP-FEIA (or Immunocap) RAST test is a specific type of RAST (see above). It is also a blood test. Immunocap is a brand name of a type of RAST test. This is the brand that was used in many of the research studies of food allergies. This test is different from generic RAST tests because it allows your doctor to measure exactly how much IgE is present to a specific food or allergen. It is more exact than a generic RAST. The information from this test, in addition to the skin pri
