A Comparison of Antibody Testing, Permeability Testing, and Zonulin Levels with Small-Bowel Biopsy in Celiac Disease Patients on a Gluten-Free Diet

Active celiac disease is associated with positive endomysial (EMA) and tissue transglutaminase (TTG) antibodies, elevated zonulin levels, and increased intestinal permeability. There is little known about what happens to these immunologic and structural abnormalities in patients on a gluten-free diet and their correlation with small-bowel biopsy changes. Adult patients previously diagnosed with celiac disease and on a gluten-free diet for greater than 1 year were considered for the study. All patients underwent the following: measurement of EMA and TTG antibodies, serum zonulin levels, intestinal permeability (IP) testing with lactulose/mannitol ratios, food diary analysis for gluten ingestion and small-bowel biopsy. A total of 21 patients on a gluten-free diet for a mean of 9.7 years completed the study. There were ten patients who had normalization of intestinal biopsies, IP and TTG, and EM antibodies. Six patients had Marsh type 2 or 3 lesions and all had either abnormal IP (5/6) or TTG antibody (4/6). In patients with Marsh type 3 lesions, there was a correlation between IP and zonulin levels. A subgroup of patients with celiac disease on a gluten-free diet has complete normalization of intestinal biopsies, intestinal permeability defects, and antibody levels. Patients with Marsh type 3 lesions have abnormal TTG antibodies and intestinal permeability with zonulin levels that correlate with IP. These abnormalities may be due to continued gluten ingestion. Further study is needed to determine the clinical utility of TTG antibodies and IP testing in following patients with celiac disease.