Diagnosing Celiac disease - A comparison of human tissue transglutaminase antibodies with antigliadin and antiendomysium antibodies

Objective: To evaluate and compare the sensitivity and specificity of the new serologic marker human antitissue transglutaminase antibodies (IgA anti-tTG) with those of antiendomysium (IgA EMA) and antigliadin antibodies (IgA and IgG AGA) for the diagnosis of celiac disease (CD). Methods: The level of IgA antibodies to tTG in serum was determined by an enzyme-linked immunosorbent assay (ELISA) test using recombinant human tTG as the antigen; IgA EMA, by indirect immunofluorescence; and IgA and IgG AGA, by ELISA. Sixty-eight serum samples from 59 patients with CD were studied-30 patients had untreated CD, 22 were on gluten-free diets, and 16 had been reintroduced to gluten-and compared with serum samples from 116 children examined for failure to thrive, short stature, various digestive diseases, or other non-CD conditions. Results: Twenty-eight of 30 patients with CD had anti-tTG (the 2 patients whose results were negative were 1 patient with IgA deficiency and 1 infant); 27 of 30 patients had IgA EMA (1 child was IgA anti-tTG positive and IgA EMA negative); 18 of 30 had IgA AGA; and 28 of 30 had IgG AGA. On gluten-free diets, 4 of 22 patients had anti-tTG but none had IgA EMA or IgA AGA. On normal diets, 15 of 15 children who had relapsed had anti-tTG; 9, IgA EMA; 4, IgA AGA; and 8, IgG AGA (1 child did not relapse). In subjects without CD, 3 of 116 had anti-tTG; 12, IgG AGA; and 1, IgA AGA, but none had IgA EMA. In the 3 children who had anti-tTG, CD could be excluded. The positive predictive value of IgA anti-tTG was 90% and the negative predictive value, 98%. In comparison, results for IgA EMA were 100% and 97%, IgA AGA 94% and 90%, and IgG AGA 70% and 98%, respectively. Conclusion: The presence of human anti-tTG is a reliable indicator for the diagnosis and follow-up of CD.