Celiac disease (CoD) is a gluten sensitive enteropathy. The diagnosis of CoD is based on intestinal biopsy revealing typical villous atrophy (flat mucosa). Diagnostics of CoD is not easy since a large proportion of the patients have no symptoms (silent or latent disease) or have varying atypical symptoms.
Today adult CoD patients may present with osteoporosis, neurological disorders, infertility, type 1 diabetes or other autoimmune diseases. Relatives of CoD patients have increased risk for the disease. The autoimmunity is triggered by ingested gluten (gliadin) leading to immune response to the major target autoantigen tissue transglutaminase (tTG). Antibodies to tTG and the triggering antigen (gliadin) appear in almost 100% of the patients with active CoD.
The serologic tests for IgA antibodies to endomysium of smooth muscle, tissue transglutaminase or gliadin have proved sensitive and specific in screening for these diseases.
Combination of all of these tests gives the best diagnostic sensitivity. The IgA antibody titres decrease or become negative in patients on gluten-free diet (GFD) but reappear when gluten is ingested and thus reflect compliance with the diet. A small percentage of the patients (2%) have IgA deficiency and can be diagnosed with IgG class antibody tests.