Food Allergy Testing – Skin Prick (Scratch) Test

Now that Mitch is two years old, our allergist agreed that it was time for additional food allergy testing to find out if Mitch has outgrown any of his current allergies or if he has any new food allergies to suspect foods.

Our last few attempts at retesting Mitch via an IgE RAST test has been anything but successful. Mitch has rolling veins that no phlebotomist can get, and attempting to find his veins is not only torturous for him, but for us as parents as well. After talking to his allergist about our situation, we decided to try a round of skin prick (scratch) tests and compare the results to his earlier IgE RAST tests.

Food Allergy Testing – Skin Prick (Scratch) Test

We tested Mitch for 26 different allergens including 19 allergens he had previously tested positive for, and a few new suspected allergens we found. Though this test can be uncomfortable, little Mitch was a champ lying quietly while playing Angry Birds. (Thank goodness for iphones! How did our parents ever do things without all these gadgets to keep kids busy?) Around 15-20 minutes later we had our results, and Mitch was cleaned up and slathered in Benadryl.

We couldn’t believe the test results! Eight of the nineteen allergens Mitch previously tested positive for did not produce a wheal, and another six allergens produced a wheal that was 3mm or less, a size that is commonly counted as a negative reaction. Three more allergens had a wheal of 4-5mm. We were blown away after we were given the OK to do home oral food challenges with all of Mitch’s allergens except for peanuts (11mm wheal), tree nuts (0-20mm wheal) and barley (7mm wheal).

Could Mitch really be outgrowing some of his food allergies?

Food Allergy Testing – Skin Prick Test

If you’re unfamiliar with skin prick (scratch) testing, a microscopic amount of an allergen is introduced to a patient’s skin by various means including a prick test or scratch test (the pricking the skin with a needle or pin containing a small amount of the allergen) or a patch test (by applying a patch to the skin, where the patch contains the allergen).

If an immuno-response is seen in the form of a rash, urticaria (hives), or (worse) anaphylaxis it can be concluded that the patient has a hypersensitivity (or allergy) to that allergen. Further testing can be done to identify the particular allergen.

Some allergies are identified in a few minutes but others may take several days. In all cases where the test is positive, the skin will become raised, red and appear itchy. The results are recorded- larger wheals indicating that the subject is more sensitive to that particular allergen. A negative test does not mean that the subject is not allergic; simply that either the right concentration was not used or the body failed to elicit a response.

Source: Wikipedia

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  1. Christine says

    Thanks Stacy for sharing!
    We just finished our skin testing with our little girl 2 1/2. It is so hard to watch them go though the testing. But at the same time she is so much more healthy now, than she was. She did not show that she was growing out of anything, and we added coco and pineapple. But we know their will be a day :) I think we are avoiding 12 things. I have the same picture you have, and the only way we got through it was our iPhone :) Thank you for all your posts and encouragement. It has been wonderful to hear your story and ideas as we have been walking though food allergies with our baby girl! Thank You!

    • says

      Thank you for the wonderful comment!

      It is a difficult journey, especially when they are so young and innocent. But I do agree, even though it can be hard to go through the testing it is worth it when we can make them healthier.

      I’ll be posting about some of our trials over the next few weeks. We’ve tried wheat, egg, milk, corn and soy. Some have worked, some have not, and some unfortunately we’re having to re-challenge.

      I wish the best for your little girl and family. :)


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