Nearly everyday I have patients referred to my office from other physicians to help interpret blood tests looking for allergies. All too often, a physician who lacks training in the diagnosis and treatment of allergic disease will order a screening allergy blood test, which measures the amount of IgE, or allegic antibody, in the blood. These screening tests check for a wide range of allergens, including pollens, molds, animal dander, dust mites, and typically a wide variety of foods. While this may sound like a good thing, false positive results are extremely common. For example, particularly in atopic children, it is common for allergy blood tests to show positive results to at least some foods. However, if the child can eat those foods without experiencing symptoms of an allergic reaction, then that child is not allergic to the food in question. The same can be said for environmental allergens -- if a person's blood test shows allergic antibodies towards dog dander, but that person experiences no allergic symptoms with dog exposure, then they aren't allergic to dogs. The bottom line is that allergy tests don't diagnose allergies -- taking a good medical history, and using allergy testing as a confirmation, makes the diagnosis of allergies.
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