Modern diagnosis of celiac disease and relevant differential diagnoses in the case of cereal intolerance.

At an incidence of 1:500, celiac disease (formerly sprue) is an important differential diagnosis in patients with malabsorption, abdominal discomfort, diarrhea and food intolerances. Celiac disease can induce a broad spectrum of both gastrointestinal and extraintestinal symptoms, e.g. dermatitis herpetiformis (Duhring's disease). A variety of oligo- and asymptomatic courses (e.g. anemia, osteoporosis, depression) through to refractory collagenic celiac disease are seen. In HLA-DQ2 and -8 predisposed individuals, celiac disease is provoked by contact with wheat gliadin fractions through a predominantly Th1 immune response and an accompanying Th2 response, which can eventually lead to villous atrophy. Using appropriate serological tests (IgA antibodies against tissue-transglutaminase, endomysium and deamidated gliadin peptides) under sufficient gluten ingestion, the diagnosis can be made more reliably today than previously. The same IgG-based serological tests should be used in the case of IgA deficiency. Diagnosis can either be made in children and adolescents with anti-transglutaminase titers exceeding ten times the standard for two of the above-mentioned serological markers and HLA conformity or it is made by endoscopy and histological Marsh classification in adults and in cases of inconclusive serology. If clinically tolerated, gluten challenges are indicated in patients that already have reduced gluten intake, in borderline serological results, discordance between serological and histological results or in suspected food allergy. The diagnosis of celiac disease needs to be definitive and robust before establishing a gluten-free diet, since lifelong abstention from gluten (gliadin < 20 mg/kg foodstuffs), cereal products (wheat, rye, barley and spelt) as well as from preparations and beverages containing gluten, is necessary. With effective elimination of gluten, the prognosis regarding complete resolution of small bowel inflammation is good. Refractory courses are seen only in rare cases, accompanied by enteropathy-associated T-cell lymphoma.