Anti-Tissue Transglutaminase IgA Antibodies

Celiac disease is the most common genetically related food intolerance, worldwide. It is an immune mediated intolerance to gluten (from wheat, barley, or rye) in genetically susceptible individuals .The disease primarily affects the small intestine, where it progressively leads to flattening of the small intestinal mucosa .

Within this definition, patients can further be defined as having silent, potential, or latent celiac disease. The term silent celiac disease refers to patients fulfilling the definition above, but presenting no symptoms. Typically, such diagnoses are made by screening asymptomatic individuals, who are at increased risk for celiac disease. The term potential celiac disease describes patients who have specific serum autoantibodies and may or may not have symptoms consistent with celiac disease, but lack evidence of the autoimmune damage to the intestinal mucosa. A final category of celiac patients is represented by the so-called latent celiac disease: individuals with normal mucosal morphology (like the potential) but known to have had a gluten-dependent enteropathy at some point in their life . Malabsorption results from injury to the small intestine with loss of absorptive surface area, reduction of digestive enzymes, and consequential impaired absorption of micronutrients such as fat-soluble vitamins, iron and potentially B12 and folic acid. In addition, the inflammation exacerbates symptoms of malabsorption by causing net secretion of fluid that can result in diarrhea. The failure of absorption of adequate calories leads to weight loss, and the malabsorption results in abdominal pain and bloating . A positive family history is a risk factor for celiac disease. The frequency of celiac disease is higher among first- and second-degree relatives of persons with celiac disease, although prevalence estimates range from 5 to 20 percent . Frequency of celiac disease is also higher among persons with other autoimmune diseases, such as type 1 diabetes mellitus, inflammatory luminal gastrointestinal disorders, Down syndrome, Turner's syndrome, IgA deficiency, and IgA nephropathy . Gastrointestinal and extra-intestinal manifestations of celiac disease include diarrhea, abdominal pain, abdominal distention, anorexia, vomiting, constipation, failure to thrive, chronic fatigue, anemia, osteoporosis, aphthous stomatitis, elevated liver enzymes, joint/muscle pain, epilepsy, and peripheral neuropathy . Clinical practice guidelines recommend to starting with the serum anti-tissue transglutaminase IgA antibodies (anti-tTG IgA) test as a diagnostic testing for celiac disease. The tTG IgA test is the standard method of testing for celiac disease . Clinical practice in guidelines the United States and Europe recommend intestinal biopsy to confirm the diagnosis of celiac disease (e.g., based on presence of villous atrophy hyperplasia of crypts, and increase of intraepithelial lymphocytes) and to distinguish celiac disease from other disorders affecting the small intestine. Intestinal biopsy may also be performed if clinical suspicion for celiac disease is high but serologic tests are negative . It has been suggested that a combination of serologic tests could be used to establish celiac disease diagnosis as an alternative to biopsy, but it is unclear how frequently celiac disease is diagnosed in the absence of biopsy in clinical practice.