Celiac disease: diagnostic criteria in progress

Abstract

Until a few years ago, celiac disease (CD) was thought to be a rare food intolerance that was confined to childhood and characterized by severe malabsorption and flat intestinal mucosa. Currently, CD is regarded as an autoimmune disorder that is common in the general population (affecting 1 in 100 individuals), with possible onset at any age and with many possible presentations. The identification of CD is challenging because it can begin not only with diarrhea and weight loss but also with atypical gastrointestinal (constipation and recurrent abdominal pain) and extra-intestinal symptoms (anemia, raised transaminases, osteoporosis, recurrent miscarriages, aphthous stomatitis and associated autoimmune disorders), or it could be completely symptomless. Over the last 20 years, the diagnostic accuracy of serology for CD has progressively increased with the development of highly reliable tests, such as the detection of IgA tissue transglutaminase and antiendomysial and IgG antideamidated gliadin peptide antibodies. The routine use of antibody markers has allowed researchers to discover a very high number of 'borderline' cases, characterized by positive serology and mild intestinal lesions or normal small intestine architecture, which can be classified as potential CD. Therefore, it is evident that the 'old celiac disease' with flat mucosa is only a part of the spectrum of CD. It is possible that serology could identify CD in its early stages, before the appearance of severe intestinal damage. In cases with a positive serology but with mild or absent intestinal lesions, the detection of HLA-DQ2 and HLA-DQ8 can help reinforce or exclude the diagnosis of gluten sensitivity.

Figure 1

Different grades of small intestinal damage in coeliac disease patients: a-b normal villi and pathological increase of intraepithelial lymphocytes (IELs) (a- haematoxilin/eosin, b CD3 staining), c-d mild/moderate atrophy of villi and pathological increase of IELs (c- haematoxilin/eosin, d staining), e-f total villous atrophy and pathological increase of IELs (e- haematoxilin/eosin, f CD3 staining). Magnification x20.

Figure 2

Comparison between the present and the new serological strategy for coeliac disease diagnosis. The combined search for IgG DGP-AGA to IgA tTGA in the diagnostic work-up of coeliac disease makes unuseful the detection of IgA EmA, IgG tTGA and IgA AGA. Abbreviations: tTGA, antibodies to tissue transglutaminase, EmA, antiendomysial antibodies, DGP-AGA, antideamidated gliadin peptide antibodies, AGA, antigliadin antibodies, CD, celiac disease.