Blood Test For Food Allergies
Why blood test for food allergies?
Blood tests for food allergies measure the presence of the IgE antibodies to the specific foods. IgE is the short form for the immunoglobulin E which is the antibody that triggers the food allergy symptoms in a person. In the past, such blood tests were called as the “RASTs” that stands for the radioallergosorbent tests. It is because they used the radioactivity, however, modern tests do not use radioactivity.
Blood Test for food allergies:
As we have established the fact earlier that the Blood tests for food allergies measure the presence of the IgE antibodies to the specific foods. IgE is the short form for the immunoglobulin E which is the antibody that triggers the food allergy symptoms in a person. In the past, such blood tests were called as “RASTs” that stands for the radioallergosorbent tests. It is because they used the radioactivity, however, modern tests do not use radioactivity.Both the blood test and the skin prick tests can detect the food specific IgE. For the skin tests, the result is immediate, but the for blood test result will take at least some days to arrive. It is different from the skin prick test in the sense that the blood test is not affected by the antihistamines and could be performed for the people with the extensive rashes that prevent using or carrying out the skin tests.
Different types of laboratories sometimes use some different brands of the blood test and they might report results using some different scoring systems or different units. The allergist must be aware of the differences because the tests and the reporting systems are not not possible to make them interchangeable.
The allergist should explain meaning of the blood tests to you so that you may know what it is it. The results are not helpful for predicting the severity of the allergy. Instead, the tests givesinformation about the chance whether there is an allergy or not. This test is not like the some other tests which only give the result yes or no. positive or negative. Often the blood test for food allergy are positive, but the person is able to eat food without the symptoms because they are not allergic. There are number of possible reasons that the test may be positive however, the person is not truly allergic to some food
About 50 to 60 percent of all the blood tests for food allergies and the skin prick tests will yield the false positive result. It means that the tests show positive even though you are not really getting allergic to the food being tested with the test. These results occur because of two reasons:
- First reason is that, The blood test for food allergies may be measuring the response to undigested food proteins. It is possible that once after digestion, the food protein which enters the bloodstream is no longer detected by the IgE.
- Second reason being, the test might be detecting the proteins that are similar among foods however they do not trigger the allergic reactions. For instance if you are allergic to the peanuts, your tests might show the positive response to some other members of the legume family, like as green beans. even in case if you are eating green beans and they has never been a problem for you.
Despite of the high chance that the blood test or the skin test may be positive despite of there being no allergy, or very rarely negative ,despite there being the allergy, in the hands of the experienced allergist, the blood and the skin tests are extremely helpful in this sense. This is especially true when results are interpreted in context of the medical history. For instance, if the history suggests that you have several reactions after eating the soy products, and blood tests show the positive reaction to the soy proteins, it is much likely that you do have the soy allergy. The allergist may order the additional tests, if they are necessary to carry out.
That was all about blood test for food allergies. After reading this article you will be able to know what are the blood test for food allergies