Need for quantitative assessment of transglutaminase autoantibodies for celiac disease in screening-identified children

Objectives To assess several transglutaminase autoantibody (TGAA) assays in their ability to distinguish celiac disease (CD) in screening-identified children with abnormal intestine biopsy specimens from those with normal biopsy specimens. Study design Children at risk for CD (n = 54) composed of type I diabetics, first-degree relatives of type I diabetics or CD, and HLA-DQ2+ individuals followed from birth received intestine biopsy. Sera obtained at the time of biopsy were tested for TGAA, using the radioimmunoassay and 5 other commercially available enzyme-linked immunosorbent assays. Results False-positive rates ranged from 28% to 80%. The positive predictive value (PPV) of the tests ranged from 63% to 84% (lower than reported for symptomatic children). Setting a higher cutoff for each assay maximized PPV. Conclusions There are significant quantitative differences among all TGAA assays that could affect interpretation of a positive test for CD. The overall false-positive rate for all assays was high in this population. Using the assay as a quantitative rather than qualitative tool by increasing the cutoff of positivity to indicate biopsy increases PPV. Multicenter workshops are needed to identify critical differences and to standardize TGAA assays among laboratories.