Notably, cases consumed a median of 4.9 g of gluten a day before tTGA seroconversion, 1 g more than the median amount for controls of the same age (odds ratio, 1.3; 95% confidence interval, 1.1-1.5; P = .0002).
"The prospective design of this birth cohort study enabled us to obtain the diet information before seroconversion of tTGA as a marker of celiac disease," they said.
(63) These individuals are more likely to have either normal villous architecture with increased IEL counts or mild degrees of villous atrophy, and they likely lack a humoral response to the autoantigens--tissue transglutaminase or gliadin.64 The sensitivity of serum anti-EMA or tTGA antibody-based tests is low, reportedly 31% to 70% for CD with mild villous atrophy.
(93) The titers of autoantibodies for CD, including tTGA and EMA, have been shown to correlate with a greater degree of villous atrophy; hence, celiac patients with normal villous architecture are less likely to have positive celiac serologic test results.
Sensitivities and Specificities of Immunoglobulin A (IgA)-Class Antibodies Against Endomysial Antigen (EMA), Tissue Transglutaminase (tTGA), and Deamidated Gliadin Peptides (DGPs) IgA-Class Antibodies Sensitivity, % Specificity, % EMA 89-92 (55,57,58) 98-100 (55-58) tTGA 93-97 (54,55,61) 95-97 (54,56,58) DGPs 84-88 (57,61) 94-99 (57,61) Table 2.
Confirmatory testing is indicated based on the results of the initial tTGA serology.
However, the institute recommends against screening with antigliadin antibody (AGA), as this test is less sensitive and specific than tTGA or EMA.