What Do Positive And Negative Skin Or RAST Tests Mean?

Question: What do positive and negative skin or RAST tests mean?

Answer: In order to diagnose a child or an adult with food allergy, we use several different tools in order to do that. One is prick skin testing, and another is a test called a RAST test-- and this stands for radioallergosorbent test. That is a serum test that measures allergy antibody.

A positive test to either one of these indicates that a patient may be allergic to that food. It must be correlated back with the clinical condition of that child or adult when eating that food to determine the relevance of that positive test.

A negative test, especially in IgE antibody mediated food allergy, is very reliable to suggest that that patient may not have an allergic reaction or a serious life threatening reactions. We certainly know of exceptions to both of these rules, but a positive test really requires that you see your physician -- that a physician correlate your clinical history back with that positive test to understand if that food should be out of your diet.

Next: Are Different Types Of RASTs Like IgG Rasts Useful?


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