Commercial Tissue Transglutaminase (tTG) Lab Screenings May Miss Many Cases of Celiac Disease

Celiac.com 12/12/2004 - A new study that was presented on November 1, 2004 by Julian Abrams, MD, and colleagues from Columbia University Medical Center in New York City at the American College of Gastroenterology (ACG) 69th Annual Scientific Meeting indicates that using only antibody to tissue transglutaminase (tTG) to diagnose celiac disease will likely result in missed diagnoses—and the accuracy of the tTG results depends on which lab conducts the test. Many clinical studies during the past few years have indicated that tTG testing is as accurate as endomyosial antibody (EMA), which has caused many labs to use tTG rather than EMA, and even the recent National Institutes of Health Consensus Conference on Celiac Disease advocated the use of tTG over EMA.

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In the study the researchers evaluated the effectiveness of tTG in a general referral practice medical setting by reviewing 137 patients who had duodenal biopsy and tTG testing for celiac disease, out of which 117 were biopsy confirmed. Serum from these individuals was sent to four different commercial laboratories for analysis, and the results from these labs were compared. The average tTG sensitivity overall was 71% with a specificity of 67%. In patients with total villous atrophy sensitivity was as high as 92%, and in those with only partial villous atrophy it was as low as 38%. One of the four laboratories tested samples from 48 of the patients and their sensitivity was only 51%, while the specificity was 100%.

According to these results it appears that tTG testing—at least outside of the clinical study setting—may not be accurate, and its accuracy depends heavily on which lab is used. Unfortunately the researchers did not reveal the names of the commercial laboratories used in their study, but we hope they will do so when the study is published.