The importance of anti-transglutaminase IgA antibody detection in the diagnosis of celiac disease – case report of an inappropriate diagnostic approach

Celiac disease (CD) is a chronic autoimmune intestinal disease caused by intolerance to gluten [1]. It is characterised by immune-mediated enteropathy, associated with maldigestion and malabsorption of most nutrients and vitamins. The clinical presentations of CD differ depending on the patients' age. Children younger than 2–3 years of age in most cases suffer from classical CD, whereas older children and adults usually present with atypical forms [2, 3]. Until recently, firm diagnosis of CD has been established based on small intestinal biopsy; however, in 2012 the European Society for Paediatric Gastroenterology, Hepatology, and Nutrition (ESPGHAN) re-edited their diagnostic guidelines for CD in children [1]. According to the new recommendations (Table I), the presence of IgA anti-intestinal transglu-taminase 2 antibody (TGA-IgA) is the most sensitive serological marker, and detection of those specific anti-bodies together with determination of total IgA should be the first tests when CD is suspected in symptomatic children. According to the novel recommendations, the diagnosis of CD without biopsy is allowed in certain cases [4]. Such a diagnostic approach concerns patients who present with clinical CD symptoms and strictly fulfil the following criteria: 1) TGA-IgA are highly elevated (greater than 10 times the upper limit of normal values), 2) antibody positivity is verified by IgA anti-endomysial antibodies (EMA) from a blood sample taken separately from the initial test, 3) positive HLA-DQ2 or/and-DQ8 haplotypes are confirmed by genetic tests, and 4) the response to a gluten-free diet is observed. Nonetheless, histological evaluation of duodenal specimens with the use of modified Marsh-Oberhuber classification is still preferred in other cases, including patients with IgA deficiency , in whom only the antibodies in the IgG class are present. The histological criteria include the number of in-traepithelial lymphocytes (IEL) per 100 enterocytes in the small intestine, the presence of crypt hyperplasia, and/or villous atrophy. Increased IEL number is actually considered the most important histological feature indicative of CD because atrophy of small intestinal mucosa with an absence of normal intestinal villi may occur in many entities such as microvillus inclusion disease , autoimmune enteropathy, intolerance to food (e.g. cow's milk, eggs, or soya), and eosinophilic gastroen-teritis [5]. Previously, CD was diagnosed with the presence of flattened duodenal villi (grade 3 according to Marsh-Oberhuber scale). The new criteria assume that shortened villi (grade 2) are enough to recognise CD, and the disease should be suspected in symptomatic patients with a significantly increased number of …