Snapshot A 43-year-old man from Ireland presents to the clinic with complaints of diarrhea. He reports she has been having 3-5 nonbloody, loose stools per day for the last 6 months and improves when he fasts. He denies hematochezia, melena, weight loss, or family history of colon cancer. A physical examination demonstrates blistering skin lesions at the extensor surfaces of the elbow bilaterally. Introduction Clinical definition chronic autoimmune disorder triggered by an environmental agent (gliadin component of gluten) in genetically predisposed individuals often found in wheat and other grains such as barley and rye often develops in childhood but may develop at any age Genetics no single genetic marker exists majority of patients have the variant HLA-DQ2 or HLA-DQ8 allele these predisposing HLA risk alleles are necessary but not sufficient to develop celiac disease Associated conditions other autoimmune diseases (e.g., diabetes mellitus type 1) Epidemiology Demographics occurs primarily in whites of northern European ancestry > 1:5000 in North America ETIOLOGY Pathogenesis upon exposure to gluten, an abnormal immune response leads to the production of several different autoantibodies that affects different organs leads to the formation of an immune complex in the intestinal mucosa (primarily at the small intestine) presence of the immune complex promotes the aggregation of killer lymphocytes, which cause mucosal damage leads to the loss of villi lining (villous atrophy) and proliferation of crypt cells damage of the villi lining leads to dysfunction in nutrient absorption, leading to malabsorption and anemia Presentation Symptoms steatorrhea can lead to fat soluble vitamin deficiencies abdominal pain bloating flatulence weight loss/failure to gain weight fatigue some patients are asymptomatic repeated infections (if IgA deficient, common in celiac patients) anaphylaxis if transfused by IgA containing blood products Physical exam abdominal distension pallor mouth ulcers short stature dermatitis herpetiformis pruritic, red, papulo-vesicular lesion commonly on shoulders, elbows, and knees due to IgA deposits (anti-epidermal transglutaminase) in the upper dermis Studies Diagnostic testing diagnostic approach diagnosis is based on clinical symptoms and confirmed with small bowel biopsy studies serological blood tests best initial test anti-tissue transglutaminase (tTg)-IgA antibody anti-endomysial-IgA antibody tests for IgA antibodies, will be negative in those with IgA deficiency for patients with IgA deficiency, deamidated gliadin peptide (DGP) IgG testing is available positive serology requires small bowel biopsy for confirmation of diagnosis upper endoscopy with small bowel biopsy best confirmatory test at least 4 duodenal biopsies are recommended endoscopic features including loss of folds, visible fissures, nodularity, scalloping, and prominent submucosal vascularity histologic features include increased intraepithelial lymphocytes and plasma cells atrophic mucosa with loss of villi enhanced epithelial apoptosis crypt hyperplasia HLA testing only useful in ruling out celiac disease laboratory studies CBC, iron studies, folic acid, vitamin B12 to evaluate level of malnutrition/malabsorption dual energy X-ray absorptiometry (DEXA) to identify risk of fracture and need for bone protection medication Differential Inflammatory bowel disease distinguishing factors different histological appearance on biopsy Irritable bowel syndrome distinguishing factors will have negative biopsy results Treatment First-line gluten-free diet allows healing of the intestinal mucosa and resolution of all symptoms eliminates the heighted risk of osteoporosis and intestinal cancer dietary supplements Second-line steroids or immunosuppressant (e.g., azathioprine) consider in patients with refractory disease Complications Iron deficiency anemia Osteoporosis Infertility Neurological problems (secondary to malabsorption) Intestinal lymphoma develops in 10-15% of patients