Be vigilant for patients with coeliac disease.

Recent population studies show that coeliac disease affects around 1 in 100 people. The estimated ratio of diagnosed to undiagnosed individuals is 1:8, and the average delay in diagnosis is reported to be 11 years. The contemporary coeliac patient is diagnosed between the ages of 40 and 60, has normal or even high BMI, and subtle symptoms. Patients are often identified in screening groups which would include those with type 1 diabetes, autoimmune thyroid disease, or a first-degree relative with coeliac disease. The presence of relevant symptoms is not essential for a diagnosis of coeliac disease. Additionally, positive serological testing alone is not sufficient to confirm the diagnosis. Endomysial antibody (EMA) and tissue transglutaminase (TTG) have a combined sensitivity and specificity of > 90% when used in combination in selected populations. However, false positives occur in conditions such as inflammatory bowel disease, and autoimmune disease. Conversely antibody-negative disease accounts for around 9% of cases. IgA deficiency is a cause of false negatives and levels should be checked at the same time as EMA and TTG. Patients must consume a gluten-containing diet for six weeks before serological testing and biopsy if necessary. All those with positive serological tests, and those for whom clinical suspicion is high even if seronegative, should be referred to a gastroenterologist for a duodenal biopsy to confirm or exclude coeliac disease. Diagnosis requires the demonstration of villous atrophy in the small bowel which improves when gluten is withdrawn.