How to diagnose food allergy

Purpose of review To assess the recent studies that focus on specific immunoglobulin E (sIgE) testing and basophil activation test (BAT) for diagnosing IgE-mediated food allergies. Recent findings The sIgE to allergen extract or component can predict reactivity to food. The cutoff value based on the positive predictive value (PPV) of sIgE can be considered whenever deciding whether oral food challenge (OFC) is required to diagnose hen's egg, cow's milk, wheat, peanut, and cashew nut allergy. However, PPV varies depending on the patients' background, OFC methodology, challenge foods, and assay methodology. Component-resolved diagnostics (CRD) has been used for food allergy diagnosis. Ovomucoid and omega-5 gliadin are good diagnostic markers for heated egg and wheat allergy. More recently, CRD of peanut, tree nuts, and seed have been investigated. Ara h 2 showed the best diagnostic accuracy for peanut allergy; other storage proteins, such as Jug r 1 for walnut, Ana o 3 for cashew nut, Ses i 1 for sesame, and Fag e 3 for buckwheat, are also better markers than allergen extracts. Some studies suggested that BAT has superior specificity than skin prick test and sIgE testing. Summary The sIgE testing and BAT can improve diagnostic accuracy. CRD provides additional information that can help determine whether OFCs should be performed to diagnose food allergy. Correspondence to Sakura Sato, MD, Department of Allergy, Clinical Research Center for Allergology and Rheumatology, Sagamihara National Hospital, 18-1 Sakuradai, Minami-ku, Sagamihara, Kanagawa 252-0392, Japan. Tel: +81 42 742 8311; fax: +81 42 742 5314; e-mail: s-satou@sagamihara-hosp.gr.jp Copyright © 2018 Wolters Kluwer Health, Inc. All rights reserved.

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