Coeliac disease is regarded as an autoimmune disorder triggered by gluten, which activates an immune reaction against the autoantigen tissue transglutaminase (transglutaminase 2; TG2) in genetically predisposed subjects. Genetic susceptibility to coeliac disease has been proven by its close linkage with major histocompatibility complex (MHC) class II human leukocyte antigen (HLA) DQ2 and DQ8 haplotypes. The identification of biomarkers for coeliac disease (e.g. endomysial antibodies [EmA] and antibodies to TG2 [anti-TG2]) has changed the epidemiology of coeliac disease from being a rare to a frequent condition, with an expected prevalence of 1% in the worldwide population.1 Nonetheless, the majority of patients who have coeliac disease remain undiagnosed, leaving the coeliac ‘iceberg’ mostly submerged. Coeliac disease can be difficult to diagnose because symptoms vary from patient to patient. Indeed, the heterogeneity among the clinical signs and the lack of specificity of many of the presenting symptoms means that the diagnosis of coeliac disease can be a challenge even for experts.
Despite substantial differences in the mode of presentation and the availability of new diagnostic tools, small intestinal biopsy, which shows different grades of mucosal damage, remains the gold standard for coeliac disease diagnosis. A delayed diagnosis of coeliac disease in the elderly can be considered a risk factor for complications including refractory coeliac disease, ulcerative jejunoileitis, collagenous sprue, small bowel carcinoma and enteropathy-associated T-cell lymphoma (EATL). Complicated coeliac disease is not so frequent, being found only in about 1–2% of the total number of coeliac disease patients, but for those who have it the prognosis is very poor, with a low rate of survival after 5 years.2
Here we discuss the major mistakes that are made when diagnosing coeliac disease and how to avoid them. The list of mistakes and the discussion that follows is evidence based and integrated with our clinical experience of more than 30 years in this field.