Which Test is the Most Reliable to Know if a Child Has Really Outgrown a Food Allergy?

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Published: January 22, 2018
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Q: Our 6-year-old was diagnosed as a toddler with multiple food allergies, following trial and error with food introduction. His allergies range from the usual suspects (dairy, eggs, peanut) to the more obscure (poultry, some legumes and garlic). We’d like to retest to see if he’s outgrown some of these, but with such a long list, are skin testing and oral food challenges the only way to know? Or would a blood test be a reliable enough indicator?

Dr. Sicherer:  A blood test alone rarely provides enough diagnostic information. In terms of an evaluation into whether a particular food allergy has resolved, or for that matter any diagnosis of food allergy, the primary tools available to the allergist include: the medical history, skin tests, blood tests and medically supervised feeding, also called an oral food challenge.

The skin and blood tests have a lot in common. They both test for an immune response against the food, but they are not perfect. For example, they may be positive in a person who can, in fact, tolerate the food. The degree of positive matters. The doctor chooses which of the tests, and perhaps both, based on the medical circumstances and may use them in a complementary fashion.

Do not underestimate the importance of the medical history, which includes symptoms such as hives after possible exposure to foods on your child’s avoidance list. Your doctor will use that information to select and interpret the tests.

It is usually not necessary to perform large numbers of food skin tests; not everything being avoided has to be tested. The foods to test should be chosen judiciously, based on the history and expectations that certain allergies may have resolved.

The oral challenge, which is considered the “gold standard” since the child actually consumes a food, is typically selected based upon the odds of tolerating the food, and the importance of the foods in the diet.

It is very likely that some foods your child is avoiding will no longer be a problem as it is common to see many of them resolve in early childhood.

I suggest at least a yearly evaluation for resolution and, when so many foods are avoided, consultation with a registered dietitian to ensure adequate nutrition.

Dr. Scott Sicherer is a practicing allergist, clinical researcher and professor of pediatrics. He is Director of the Jaffe Food Allergy Institute and Chief of Pediatric Allergy and Immunology at the Icahn School of Medicine at Mount Sinai in New York. He’s also the author of Food Allergies: A Complete Guide for Eating When Your Life Depends On It.

Read more:
What to Know: Proper Food Allergy Diagnosis & Food Allergy Testing
How Often Should Someone be Retested for Food Allergies?

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