Nonceliac Gluten Sensitivity--Is It Really the Gluten?
Diagnostic Testing for NCGS
For NCGS, there is currently no specific serologic marker. Primary-care NPs need to be aware of the range of GI and non-GI clinical presentations and refer to appropriate specialists if necessary. The diagnostic process involves exclusion of CD and wheat allergy. This involves detailed history-taking and clinical findings that include: negative immunoallergy tests to wheat by normal specific IgE; negative CD serology (anti-EMA and/or anti-tTG) in which IgA deficiency has been ruled out; normal duodenal histopathology; and the possible presence of biomarkers of native gluten immune reaction, anti-gliadin antibodies (AGA). In addition, patients present with clinical symptoms that can overlap with CD or wheat allergy symptoms, and patients show a resolution of symptoms when started on a GFD. Although positive tests for deamidated gliadin antibodies, AGA-IgA, and IgG may occur in 50% of cases and provide some support for suspicion of NCGS, specificity and sensitivity have not been established.
If symptoms do go away while on a GFD, the patient should undergo a gluten challenge to confirm. A gluten challenge may begin with one regular cracker or a one-quarter slice of regular bread; this is doubled every 1 to 3 days until significant symptoms develop or until one is eating the equivalent of 4 slices of bread or 2 cups/servings of pasta per day. However, many patients often refuse to return to gluten if they have already started a GFD on their own and have had symptom relief.