Celiac disease in the 21st century: issues of under- and over-diagnosis.

Until the 1960s celiac disease (CD) or sprue was considered a pediatric disease that was rarely diagnosed in adulthood. Thanks to greater awareness of the disease and the availability of improved diagnostic tools (above all, sophisticated endoscopic techniques and the development of reliable serological markers), the prevalence of CD in Western countries has been increasing steadily, and it is now recognized as a common disorder, even in adults. However, many cases of this disease still go undiagnosed, especially among the elderly and in patients with atypical clinical presentations (which are by no means uncommon). On the other hand, the frequency of unfounded diagnoses of CD is also on the rise. This reflects a tendency toward exclusively symptomatic diagnosis as well as the growing use of invalidated tests for CD (e.g., the cytotoxic test, the sublingual or subcutaneous provocation/neutralization test, etc.). As a result, public healthcare spending is being increased in several countries (Italy included) by the growing number of prescriptions for gluten-free diets. This editorial discusses the problems of under- and over-diagnosis of CD and provides an algorithm for management of suspected cases designed to minimize both problems with particular importance to morphologic aspects of small bowel (also in electron microscopy), in basal conditions or in gluten-free diets.