Generally, children at risk for celiac disease are screened at age 3 unless symptoms are seen beforehand. In children younger than 3, with symptoms, antibody testing is usually reliable, especially if it includes DGP-IgG. Children must be eating wheat or barley-based cereals for some time, up to several months, before they can generate an autoimmune response to gluten that shows up in testing. A pediatric gastroenterologist should evaluate young children experiencing a failure to thrive or persistent diarrhea for celiac disease.
While a genetic test cannot diagnose celiac disease by itself, it can all but rule it out if neither of the genes are present, and a genetic test
can be done at any age. June, 2017