Diagnostic approach for suspected celiac disease in an adult patient on gluten free diet and negative baseline serologies*

HLA: human leukocyte antigen; tTG: tissue transglutaminase; IgA: immunoglobulin A; IgG: immunoglobulin G; DGP: deamidated gliadin peptide.
* Testing for celiac disease should be performed in adults with suggestive gastrointestinal or extraintestinal signs/symptoms of celiac disease.
¶ A two-week gluten challenge may yield false-negative results in 10% of patients. The added diagnostic sensitivity of extending the challenge to a total of eight weeks is unknown.
Δ tTG-IgA antibody is the single preferred test for detection of celiac disease in adults. In addition, we concurrently measure total IgA levels. In patients with IgA deficiency, we perform IgG based testing with DGP-IgG.
◊ The histologic severity of intestinal lesions in celiac disease are graded using the Marsh-Oberhuber classification. Marsh 2 and 3 are consistent with a diagnosis of celiac disease in individuals with positive celiac-specific serology. Marsh 1 is equivocal and Marsh 0 is normal. Refer to UpToDate content on diagnosis of celiac disease.
§ An improvement in histology, even in the absence of complete histologic resolution, is supportive of the diagnosis of celiac disease.
¥ Individuals with positive celiac-specific serology but Marsh 0 or 1 intestinal lesions on duodenal biopsy have potential celiac disease. Individuals with potential celiac disease should be evaluated and monitored further depending upon their clinical circumstances. Symptomatic patients with potential celiac disease are likely to benefit from treatment with a gluten free diet.
‡ There are several causes of non-celiac enteropathy (villous atrophy in duodenum). Potential causes include giardiasis, small intestinal bacterial overgrowth, and common variable immunodeficiency. For a more comprehensive list of causes, refer to UpToDate content on diagnosis of celiac disease.