Evaluation for celiac disease in a child who is already on a gluten-free diet for >2 weeks

DGP: deamidated gliadin peptide; EMA: anti-endomysial antibodies; HLA: human leukocyte antigen; Ig: immunoglobulin; tTG: tissue transglutaminase.

* A gluten challenge may not be appropriate for young children (eg, <5 years) or those with severe symptoms (eg, growth restriction). For most such children, we still consider serologic screening (tTG-IgA and total IgA) even if the child is following a gluten-free diet. If the result is positive, we interpret as for children on a gluten-containing diet. If the result is negative, then a gluten challenge may be needed for proper assessment.

¶ Total IgA below the normal range indicates IgA deficiency, which is present in approximately 2% of patients with celiac disease. For these patients, the appropriate test is tTG-IgG (rather than tTG-IgA). If either of these tests is positive, proceed to endoscopy. If both of these tests are negative, celiac disease is unlikely.

Δ HLA-DQ2 or DQ8 serotypes are present in virtually all patients with celiac disease but are also common in the general population. Hence, HLA testing is only useful for ruling out celiac disease.

◊ A gluten challenge ideally consists of ingesting a minimum of 3 to 6 g/day of gluten for 8 to 12 weeks. A shorter challenge may be possible if the prior gluten-free diet was brief or inconsistent. 3 g/day of gluten is approximately 1 slice of bread or one-half cup of cooked pasta. It is prudent to arrange a follow-up visit at 4 to 6 weeks to assess symptoms and tolerance of the diet.