Clinical value of immunoglobulin A antitransglutaminase assay in the diagnosis of celiac disease.

OBJECTIVES. Our goal was to evaluate the possible correspondence between antitissue transglutaminase of immunoglobulin A class levels and stage of mucosal damage in patients affected by celiac disease. In addition, we assessed clinical use of antitissue transglutaminase values to predict biopsy results. METHODS. One thousand eight hundred eighty-six consecutive patients with symptoms suggestive of celiac disease and 305 healthy controls underwent determination of serum levels of immunoglobulin A and antitissue transglutaminase. An intestinal biopsy was performed in subjects with antitissue transglutaminase levels >= 4 IU/mL and in subjects with negative antitissue transglutaminase levels but with clinical suspicion of celiac disease. Histologic grading of celiac disease was consistent with the Marsh classification. RESULTS. One hundred eighty-six subjects with positive antitissue transglutaminase levels and 91 patients with negative antitissue transglutaminase levels were submitted to biopsy. In all healthy subjects, antitissue transglutaminase results were negative. Histologic evaluations in patients with positive antitissue transglutaminase levels gave the following results: type 0 in 25 patients, type 1 in 3 patients, type 2 in 4 patients, type 3a in 22 patients, type 3b in 74 patients, and type 3c in 58 patients. None of the patients with negative antitissue transglutaminase levels showed histologic findings suggestive of celiac disease. The mean antitissue transglutaminase values in patients without mucosal atrophy were significantly lower than in patients with mucosal atrophy. Antitissue transglutaminase values >= 20 IU/mL were found in only 1 patient without mucosal atrophy. CONCLUSIONS. Our study found a strong correspondence between antitissue transglutaminase levels and stage of mucosal injury; antitissue transglutaminase values >= 20 IU/mL seemed to be strongly predictive of mucosal atrophy.