Objective: Demonstration of small-bowel mucosal damage has been the basis of celiac disease diagnosis, but the diagnostic approach is undergoing changes. The European Society for Pediatric Gastroenterology, Hepatology, and Nutrition recently stated that in a subgroup of children, high positive transglutaminase 2 antibody (TG2ab) values may be sufficient for the diagnosis. The utility of these new criteria was evaluated by applying the human red blood cell TG2 antibody test (RBC-TG2ab) to a large cohort of children and adults belonging to at-risk groups.
Methods: RBC-TG2ab and endomysial antibodies (EmA) were measured in 3031 family members or other relatives of patients with celiac disease. The RBC-TG2ab values were classified as weak (20–29 U), moderate (30–99 U), and strong (≥100 U) positive. Seropositive subjects were further tested by human recombinant TG2ab (Hr-TG2ab) and for the presence of celiac disease–associated human leukocyte antigen-DQ alleles. Gastroscopy was recommended for all with positive RBC-TG2ab, EmA, or Hr-TG2ab, or weak positive RBC-TG2ab and symptoms.
Results: Strong positive RBC-TG2ab has good correlation with EmA and Hr-TG2ab and positivity of DQ2/8, and the diagnosis was established in 94% of both children and adults. In contrast, moderately positive (≥30 U) RBC-TG2ab showed poor correlation with the other tests, and celiac disease was diagnosed in 69% of children and 86% of adults. Most participants with weak positive RBC-TG2ab were negative for EmA and Hr-TG2ab.
Conclusions: In accordance with the new European Society for Pediatric Gastroenterology, Hepatology, and Nutrition criteria, strong positive RBC-TG2ab showed good accuracy and excellent correlation with the other antibodies and celiac-type human leukocyte antigen. In contrast, low or moderately positive RBC-TG2ab values were of unsatisfactory prognostic value for a subsequent diagnosis.