Is immunoglobulin A anti-tissue transglutaminase antibody a reliable serological marker of coeliac disease?
GROUND: Anti-tissue transglutaminase (tTG) antibody is being used increasingly as a diagnostic tool in the serological investigation of coeliac disease. However, positive predictive values of immunoglobulin A (IgA) anti-tTG for coeliac disease in prospective studies have been disappointing and false-positive results are reported. OBJECTIVE: To assess the clinical utility of cascade testing for anti-tTG and anti-endomysium antibody (AEA). PATIENTS: Two unselected retrospective cohorts from routine diagnostic investigation for possible gluten sensitive enteropathy: group 1 comprised 57 cases seropositive for anti-tTG and group 2 comprised 52 cases seronegative for anti-tTG. In both groups, all cases had also undergone small-intestinal biopsy. METHODS: Patients were assessed for the presence of IgA anti-tTG by enzyme-linked immunosorbent assay and for IgA AEA by immunofluorescence. RESULTS: The positive predictive value of IgA anti-tTG for biopsy-confirmed coeliac disease was 54%. The pos
