What are the recommended allergy tests for a 17-month-old child?

Recommended Allergy Tests for a 17-Month-Old Child

For a 17-month-old child with suspected food allergies, referral to an allergist is strongly recommended for proper diagnostic testing rather than routine screening without clinical suspicion. 1

Appropriate Diagnostic Approach

When to Test

Testing should only be performed when there is clinical suspicion of food allergy, not as routine screening. Indications for testing include:

• History of immediate allergic reactions (occurring within minutes to hours after food ingestion)
• Moderate-to-severe atopic dermatitis that persists despite optimal management
• Specific gastrointestinal symptoms suggestive of food allergies

Recommended Tests

1. Skin Prick Test (SPT)

   • Conducted by allergy specialists
   • Introduces allergen extracts into the skin
   • Positive reaction defined as wheal ≥3mm greater than negative control
   • High negative predictive value (>95%) but low positive predictive value (<50%) 1

2. Serum-Specific IgE Testing

   • Quantifies free specific serum IgE antibodies
   • Should be targeted to specific suspected allergens, not broad panels
   • Like SPT, a positive test alone does not establish clinical food allergy but indicates sensitization 1

3. Oral Food Challenge

   • Gold standard for diagnosis
   • Should be performed by specialists with experience in food challenges
   • Begins with low doses gradually increased while monitoring for reactions
   • Essential for confirming diagnosis when history and testing are inconclusive 1

Tests NOT Recommended

• Atopy patch testing for food allergies 1
• Intradermal food testing 1
• IgG4 food testing 1
• Standard food panels without clinical suspicion 1
• Skin-prick tests to aeroallergens as diagnostic tests for asthma 1

Common Food Allergens in Children

Focus testing on the eight most common food allergens in children:

• Cow's milk
• Hen's egg
• Soy
• Peanuts
• Tree nuts
• Wheat
• Fish
• Shellfish 1, 2

Important Considerations

Test Interpretation

A positive test result alone does not establish clinical food allergy. The diagnosis requires correlation with the patient's clinical history. Many children with positive tests can tolerate the food without reactions 1.

False Positives

Overreliance on serum-specific IgE testing or skin prick tests without clinical correlation can lead to unnecessary dietary restrictions. In one study, 93% of children avoiding foods due to positive test results were actually tolerant of those foods 1.

Management Following Diagnosis

If food allergy is confirmed:

1. Prescribe antihistamines for mild reactions and epinephrine autoinjector for severe reactions
2. Provide education on food avoidance and label reading
3. Create an emergency action plan
4. Schedule appropriate follow-up to assess for development of tolerance 1

Follow-up

Children with food allergies should be reassessed regularly as many develop tolerance over time, particularly to milk, egg, soy, and wheat. Far fewer will eventually tolerate peanuts, tree nuts, fish, and shellfish 1.

Remember that testing should be guided by clinical suspicion and not performed indiscriminately, as this can lead to overdiagnosis and unnecessary dietary restrictions that may affect a child's nutritional status and growth 3.