Diagnostic Approaches for Food Allergies

Recommended Diagnostic Methods

The American Academy of Allergy, Asthma, and Immunology recommends considering food allergy in individuals presenting with symptoms that occur within minutes to hours of ingesting food, especially if symptoms have followed ingestion of a specific food on more than one occasion 2
Parent and patient reports of food allergies must be confirmed, as studies demonstrate that 50-90% of presumed food allergies are not actual allergies 2
Skin prick testing (SPT) is recommended to identify foods potentially provoking IgE-mediated allergic reactions, with a high negative predictive value (>95%) but lower positive predictive value (<50%) 1, 2
Serum-specific IgE testing measures free specific serum IgE to food allergens, with high negative predictive value but lower positive predictive value, and should be limited to foods reasonably suspected of provoking reactions 1, 2
Oral food challenges are considered the gold standard for diagnosing food allergy, with double-blind placebo-controlled food challenge (DBPCFC) being the most accurate method 2, 3
Component-Resolved Diagnostics (CRD) is an emerging approach that measures IgE to specific food allergen components, and can reduce the need for oral food challenges in some cases 5

A positive test result alone (SPT or sIgE) does not establish clinical food allergy - it only indicates sensitization, and all positive and negative test results must be correlated with the patient's clinical history 1, 2
For children under 5 years with moderate to severe atopic dermatitis, limited food allergy testing (milk, eggs, wheat, soy, peanut) may be considered if they have persistent disease despite optimized management or history of immediate allergic reactions 6

Food avoidance is the first line of treatment for confirmed food allergies, and patients with confirmed food allergies should be prescribed both antihistamines (for mild symptoms) and epinephrine autoinjectors (for severe symptoms) 1
Referral to an allergist is recommended for comprehensive evaluation and management 1