The allergy blood test, often called the RAST, tests for the presence of allergic antibody, or IgE, in the blood. Over the past several years, this test has become increasingly popular. While the allergy blood test has become more accurate over the years, and can be useful in diagnosing allergies, particularly food allergies, it has its limitations. The blood test is often best used in conjunction with allergy skin testing, which is more sensitive. Contrary to what some people think, the allergy blood test does not give a yes or no answer about whether someone has an allergy. Rather, the blood test gives a statistical likelihood of whether or not an allergy exists, and falsely positive tests are common. Interpretation of allergy test results depends upon the medical history of the patient, and upon the experience and expertise of the physician who ordered the test. When the skin and blood test are inconclusive, oral challenges to foods can

help with diagnosis of food allergy. Board certified allergists have the best training and experience for interpreting allergy test results. A recent article in the Wall Street Journal discusses the limitations of food allergy testing and the importance of correct interpretation of the results. Please click here to see the full article.