Optimizing the Diagnosis of Food Allergy

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Key points

  • Accurate diagnosis of food allergies is vital to identify patients who may have severe, life-threatening allergic reactions, and to exclude suspected allergies that could lead to unnecessary dietary restrictions.

  • Traditional tests for food allergy have several limitations; skin prick testing and food-specific IgE levels are excellent tools for detecting sensitization to foods, but, often, positive tests are clinically irrelevant. Although oral food challenges are the gold standard for diagnosing

Standard diagnostic tests

The typical diagnostic routine (Fig. 1) begins with a medical history to determine whether the symptoms are potentially related to ingestion of specific foods; whether adverse reactions are allergic in nature; and, if so, the likely pathophysiologic basis. Knowledge of the epidemiology of food allergy and details of the history may identify potential triggers to which simple tests, such as SPT and sIgE, can be applied and interpreted in the context of the history and a knowledge of test

Component-Resolved Diagnostics

Allergen CRDs have garnered a lot of attention in recent years, with the hope of offering a more accurate assessment of allergic status. Instead of using crude allergen extracts consisting of a mixture of components, CRD measures IgE to individual allergen proteins. In recent years, several studies on a variety of food allergens have demonstrated that CRD can improve the specificity of allergy testing.

The usefulness of CRD has been best demonstrated in studies on peanut allergy.33 In 2004,

Future diagnostic tests

Several tests are undergoing study and may have advantages compared with currently available tests for diagnosing food allergy (Table 2).

Controversial and unproven tests

There are several tests that have been examined that are not recommended for the diagnosis of food allergy. Intradermal testing should not be used. Not only is intradermal injection of allergens overly sensitive, but it also carries a higher risk of adverse reactions than SPT.1, 83 The National Institute of Allergy and Infectious Diseases expert guidelines published in 2010 also suggest that atopy patch testing (APT) should not be used in the routine evaluation of noncontact food allergy.

Future considerations and summary

The work-up of a potential food allergy can be a complex assessment involving the clinical history, SPT, and sIgE levels, although ultimately these diagnostic tools may be inadequate to definitively diagnose a food allergy. Currently, OFCs remain the most definitive test in the diagnosis of food allergy, but they are time consuming, costly, and have the potential to elicit a severe allergic reaction. In recent years, several different testing modalities, including CRD, basophil activation

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