Diagnosing food allergies in children

The first step in addressing possible food allergies in a child is a complete diagnostic work-up consisting of the following:


We will then identify the general approach; namely, allergy vs. intolerance and IgE versus non-IgE mediated. In diagnosing and treating the cyclic food allergy, you should ask yourself, “Are there any foods that my child craves or any food that I avoid offering?” These foods may be the ones that are causing difficulties.

Interpretation of Laboratory Tests

Unfortunately, the skin and blood tests available to test allergies are not very good for identifiying IgG mediate (or cyclic) food allergies. IgG testing has not been proven helpful; it has often been called a very expensive means to a food diary. IgE blood testing and skin testing can be helpful, and we do typically perform them at our clinic.

A positive prick test or RAST indicates the presence of the IgE antibody, not clinical reactivity (~50% false positive). A negative prick test or RAST essentially excludes IgE antibody (>95 percent).

If the diagnosis is suspected of being non-IgE-mediated, an elimination challenge diet can be performed. Also, a biopsy of the intestine or skin could be considered.

The good news is that, with the exception of fixed food allergies (such as those to peanut), most children will outgrow food sensitivities. As the intestinal tract matures, fewer proteins can cross and more foods can be tolerated.

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