Tissue transglutaminase autoantibodies as predictors of celiac disease and its relationship to histopathological findings of intestinal biopsy

ABSTRACT

Celiac disease [CD] is a common autoimmune disorder, induced by the intake of gluten proteins present in wheat, barley and rye. Previously, it was considered to be a rare childhood disorder, but is actually considered a frequent condition, present at any age, which may have multiple complications. Active CD is characterized by intestinal and/or extra-intestinal symptoms, villous atrophy and crypt hyperplasia, and strongly positive IgA anti-endomysial antibody [EMA] and tissue transglutaminase [tTG] auto-antibodies. The duodenal biopsy is considered to be the "gold standard" for diagnosis. The use of screening tests for celiac disease has increased the number of patients referred for evaluation. We proposed that the subgroup of patients with very high tissue transglutaminase antibody [t-TGIgA] titers is positive for celiac disease and a small-bowel biopsy is not necessary to make the diagnosis. A gluten-free diet should be attempted and, if the patient's symptoms do not improve, then a biopsy should be performed to confirm the diagnosis. It is a retrospective study, reviewed 51 patients who underwent both t-TGIgA testing and a small-bowel biopsy was performed. We examined the impact of using t-TGIgA values of >100U and <20U as cutoff values and suggested performing biopsies for patients with t-TGIgA values of 20 to 100U, as is current practice. Twenty-nine of 51 patients demonstrated positive biopsy results. Twenty-four of 51 patients had t-TGIgA levels of >100U, with 23 of 24 exhibiting positive biopsy results. Only 3 of 8 patients with t-TGIgA values of 20 to 100U exhibited positive biopsy results. Three patients with t-TGIgA levels of <20U had positive biopsies; 2 were IgA negative and 1 had a duodenal ulcer. With the cutoff values of >100U and <20U with known IgA status, the sensitivity was 0.958 [23 of 24 cases] and the specificity was 0.941 [16 of 17 cases]. When the cutoff values were changed to >100 and <20U and IgA levels were verified, the sensitivity and specificity were very high. Patients with midrange t-TGIgA values [20-100U] or values of <20U with negative IgA status should continue to undergo biopsies for diagnosis of celiac disease