Fast Five Quiz: What Do You Know About Food Allergies?

Scott H. Sicherer, MD


November 11, 2016

Skin-prick tests are commonly used to evaluate food allergy and can even be performed on infants in the first few months of life. However, the reliability of the results depends on multiple factors, including use of the appropriate extracts and testing technique, accurate interpretation of the results, and avoidance of medications that might interfere with testing (eg, antihistamines).

Specific IgE antibodies to foods can be quantified by in vitro laboratory methods. This is another means to identify food-specific IgE, which can be helpful in evaluating food allergies. The term RAST (radioallergosorbent test) is antiquated because modern methods do not use radiation. The serum test may offer advantages over skin-prick testing when skin testing is limited by dermatographism, generalized dermatitis, or a clinical history of severe anaphylactic reactions to a given food. Both tests must be selected and interpreted in the context of the medical history because a positive test itself does not diagnose a food allergy.

Abnormal results from peripheral serum measurements of eosinophils or total IgE concentrations do not identify or confirm the diagnosis of food allergy. Likewise, normal values do not exclude diagnosis.

Basophil histamine-release assays are primarily limited to research settings and have not been shown conclusively to provide reproducible results useful for diagnostic testing in a clinical setting.

For more on the workup of food allergy, read here.


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