How is a food allergy diagnosed in the context of atopic (atopic dermatitis) dermatitis?

From the Guidelines

Diagnosing food allergies in patients with atopic dermatitis requires a systematic approach combining clinical history, elimination diets, and specific testing, with the gold standard for diagnosis being the oral food challenge, as recommended by the most recent guidelines 1.

Key Considerations

• A detailed clinical history is essential to identify potential temporal relationships between food consumption and symptom flares, as emphasized in the guidelines 1.
• Skin prick testing and serum-specific IgE testing can help identify potential allergens, but these tests indicate sensitization rather than definitive allergy, and their results must be correlated with clinical symptoms 1.
• Common food allergens in atopic dermatitis include cow's milk, eggs, peanuts, tree nuts, soy, wheat, and fish, and an elimination diet involves removing suspected allergens for 2-4 weeks while monitoring for symptom improvement, followed by systematic reintroduction 1.
• It's crucial to note that not all atopic dermatitis is food-triggered, and many patients with positive allergy tests may not have clinically relevant food allergies, highlighting the need for careful interpretation of test results and clinical correlation 1.

Diagnostic Approach

• Start with a detailed clinical history to identify potential food allergens and temporal relationships between food consumption and symptom flares.
• Use skin prick testing and serum-specific IgE testing to identify potential allergens, but recognize their limitations in diagnosing definitive allergy.
• Consider an elimination diet to remove suspected allergens and monitor for symptom improvement, followed by systematic reintroduction.
• The oral food challenge is the gold standard for diagnosis, and it should be performed under medical supervision after an elimination period.

Important Considerations

• Patients should maintain good skin care and continue topical treatments during the diagnostic process, as food elimination alone rarely controls severe atopic dermatitis completely.
• False positives are common in allergy testing, so test results must be carefully correlated with clinical symptoms to avoid unnecessary dietary restrictions and potential nutritional deficiencies.
• The diagnostic approach should be individualized based on the patient's clinical history, symptoms, and test results, and should involve a multidisciplinary team of healthcare professionals, including dermatologists, allergists, and dietitians, as recommended by the guidelines 1.

From the Research

Diagnosis of Food Allergy in Atopic Dermatitis

Diagnosis of food allergy in atopic dermatitis involves a combination of medical history, physical examination, and diagnostic tests. The following are some of the key points to consider:

• A thorough medical history is essential to identify potential food allergens and assess the severity of atopic dermatitis 2, 3.
• Diagnostic tests such as skin prick tests, atopy patch tests, and measurement of specific IgE levels can help identify food allergens 4, 5, 6.
• Double-blind, placebo-controlled food challenges are considered the gold standard for diagnosing food allergy, but they can be time-consuming and may not be necessary in all cases 2, 6.
• A combination of positive atopy patch test results and measurement of specific IgE levels can reduce the need for oral food challenges in children with atopic dermatitis 6.

Diagnostic Tests

Some of the diagnostic tests used to diagnose food allergy in atopic dermatitis include:

• Skin prick tests: used to measure IgE-mediated reactions to specific foods 4, 6.
• Atopy patch tests: used to detect non-IgE-mediated reactions to specific foods 5, 6.
• Measurement of specific IgE levels: used to assess the level of IgE antibodies to specific foods 4, 5, 6.
• Double-blind, placebo-controlled food challenges: used to confirm the diagnosis of food allergy 2, 6.

Food Allergens

Common food allergens that can trigger atopic dermatitis include:

• Cow's milk 2, 3, 6.
• Hen's eggs 2, 3, 6.
• Peanuts 4.
• Wheat 2, 3, 6.
• Soybean 5.

Clinical Relevance

It is essential to establish the clinical relevance of food allergens to ensure that the diagnosis is accurate and to develop an effective treatment plan 2, 4, 3.