Can a 20-month-old child be tested for allergies?

From the Guidelines

Yes, a 20-month-old child can be tested for allergies, but testing should be considered if the child has moderate to severe atopic dermatitis and persistent disease despite optimized management, or a reliable history of an immediate allergic reaction after ingestion of a specific food. Allergy testing is safe and effective for toddlers when performed by a pediatric allergist or immunologist. The most common methods used for young children include skin prick tests, where small amounts of potential allergens are placed on the skin to observe reactions, and blood tests (such as specific IgE tests) that measure antibodies to suspected allergens 1. Food allergies are particularly important to identify at this age, as they can cause serious reactions.

Key Considerations

• The National Institute of Allergy and Infectious Diseases (NIAID) Food Allergy Expert Panel suggests consideration of limited food allergy testing (of cow's milk, eggs, wheat, soy, and peanut) if a child less than 5 years of age has moderate to severe AD and specific criteria are met 1.
• Testing should be guided by the clinical history and the most prevalent allergies in a given population, with tree nuts, shellfish, and fish becoming relevant in subsequent childhood years 1.
• Positive test results may reflect sensitization, but have poor correlation with clinical allergic responses, and therefore require clinical correlation and confirmation to establish presence of allergic disease and the exact type of allergic response 1.
• The gold standard test for diagnosing food allergy is a double-blind, placebo-controlled oral food challenge (DBPCFC), but open-label or single-blind oral food challenges are more commonly used in clinical practice to screen for reactions 1.

Testing and Management

• Parents should prepare by avoiding antihistamines for 5-7 days before skin testing, as these medications can interfere with results.
• After testing, the allergist will develop an appropriate management plan based on the results, which may include avoidance strategies, emergency medication prescriptions like epinephrine auto-injectors, or in some cases, referral for oral immunotherapy 1.
• Comprehensive counseling regarding food allergy includes food avoidance and appropriate nutritional monitoring, label reading, recognition of the signs and symptoms of anaphylaxis, and how and when to use the epinephrine autoinjector 1.

From the Research

Allergy Testing in Children

• Allergic diseases are common in childhood and can cause significant morbidity and impaired quality of life for children and their families 2.
• Children with persisting or recurrent symptoms suggestive of allergy should undergo an appropriate diagnostic work-up, irrespective of their age 2.
• Skin prick tests (SPTs) are considered a rapid and effective tool for the diagnosis of pediatric allergies, and are generally safe, with few reported adverse reactions in children 3.

Age Considerations for Allergy Testing

• There is evidence to suggest that SPTs can be performed in infants, but with caution, as there have been reports of generalized allergic reactions in infants under 6 months of age 3, 4.
• One study found that the risk of generalized reactions after SPT with fresh food specimens in young children is higher in infants under 6 months of age, with a rate of 6,522 per 100,000 tested children 4.
• However, another study found that SPTs can be safely performed in children, including infants, without an increased risk of generalized allergic reactions 3.

Diagnostic Approaches for Allergy Testing

• The diagnostic gold standard for food allergy is the oral food challenge (OFC), which can be safely performed in a controlled setting by expert allergists 5.
• SPTs can be used to predict the outcome of OFCs, with a predictive cut-off value of 9 mm for albumen, 7 for yolk, and 13 for fresh albumen 5.
• However, SPTs may not be necessary in all cases, and allergy testing in children can be reduced, especially in cases of asthma and allergic rhinitis 6.

Testing for Allergies in 20-Month-Old Children

• Based on the available evidence, it appears that a 20-month-old child can be tested for allergies using SPTs or OFCs, but with caution and under the guidance of an expert allergist 2, 3, 5.
• The decision to perform allergy testing in a 20-month-old child should be based on the presence of symptoms suggestive of allergy and the potential benefits and risks of testing 2, 6.