Food Allergy Tests Yield Misleading Results, Angry Kids Demanding Their Due Peanut Butter Cups

Before you deprive your supposedly peanut-allergy-ridden child of a lifetime of delicious Reese’s Peanut Butter Cup Eggs, you may want make sure it’s necessary — because, turns out, many kids whose allergies were diagnosed on the basis of blood or skin tests alone may not be truly allergic to those foods, experts say.

Oops.

Why are they saying this?  Well, according to researchers who know slightly more than I do about this stuff (just slightly), blood tests measure the level of antibodies, called immunogloblin E (IgE), a body makes to a particular food.  However, having IgE antibodies doesn’t mean that a person will actually have an allergic symptom when they encounter it.  In fact, several recent studies have underscored the gap between IgE antibodies and actual allergies. In this month’s Journal of Allergy and Clinical Immunology — which I’m sure we ALL have in our bathroom magazine rack for a little “leisure reading” — researchers in England reported that when 79 children who tested positive for peanut IgE antibodies were given food challenges, 66 of them could eat peanuts safely.  And at the American Association of Allergy, Asthma and Immunology conference last year, doctors reported that of 125 young patients given food challenges, more than half could tolerate foods they’d been told to avoid.

Skin-prick tests are slightly more predictive, but there, too, a red wheal in response to a skin prick doesn’t necessarily mean that a child will have an actual allergic reaction to that food.

So what the hell are we parents supposed to do?  The only way to know for sure — short of encountering the food in real life, which is no fun, no fun at all — is with a food challenge test in a doctor’s office or hospital.  Not a thrilling option because those can be time consuming, expensive and nerve-wracking, especially for parents who have seen a child encounter an anaphylactic shock, a life-threatening reaction in which multiple organs quickly shut down.  (Just writing that sentence makes my heart pound.)

And NONE of those tests can predict how severe an allergic reaction might be.  A person with a peanut allergy might react with a tingle in the mouth, a case of hives or a full-blown anaphylaxis, depending on many variables, including how much peanut they ingested and in what form.

Okay, so maybe the researchers don’t know much more than I do, after all.