Looking for celiac disease: diagnostic accuracy of two rapid commercial assays

BACKGROUND: Early diagnosis and treatment with gluten-free diet reduces mortality and the prevalence of associated disorders in celiac disease (CD). A simple "in the office" test of anti-transglutaminase antibodies might be of great help in first-line screening for CD. AIMS: We evaluated the sensitivity and specificity of two commercial kits based, respectively, on rapid detection of IgA-IgG anti-human-transglutaminase antibodies (anti-h-tTG) in serum and IgA anti-h-tTG antibody in one drop of whole blood. These assays were compared to a well-established enzyme-linked immunosorbent assay technique. METHODS: Serum samples were analyzed from 114 biopsy-confirmed celiacs, 120 healthy controls, 20 first-degree relatives of celiacs, and 75 diseased controls. The whole blood samples were analyzed from 51 biopsy-confirmed celiacs and 100 controls. RESULTS: The serum-based test was positive in all 114 celiacs (sensitivity 100%). Among the controls there were seven healthy blood donors, one first-degree relative, and three diseased controls who tested positive (specificity 94.9%). The blood drop-based assay testing IgA antibodies was positive in 46 of 51 (sensitivity 90.2%), and since three of the five patients testing negative had total IgA deficiency, the sensitivity value can be increased to 95.8%. All 100 controls tested negative (specificity 100%). CONCLUSIONS: The commercial kits described here produce high values of sensitivity and specificity, offering the general practitioner who suspects a possible case of CD the real possibility to look for anti-h-tTG antibodies in his own medical office during a standard visit at a satisfyingly low cost.