Inter- and Intra-assay Variation in the Diagnostic Performance of Assays for Anti-tissue Transglutaminase in 2 Populations

Tissue transglutaminse-2 (TG2)–based immunoassays are the cornerstone of diagnosis in celiac disease (CeD), with a reported pooled sensitivity as high as 98%.1 However, a few small, single-center studies have questioned their sensitivity in clinical practice.2–5 Moreover, commercial kits use variable TG2 antigens,6 with cutoffs determined by using small, poorly defined populations. Variation in diagnostic performance of anti-TG2 assays in different racial and geographic populations has not yet been studied. We compared the interassay and intra-assay variations in diagnostic performance of 4 immunoglobulin (Ig)A–anti-TG2 assays in Canadian and Indian populations.