A 25-year-old woman comes to the office due to progressive fatigue and dizziness for several months. She also has intermittent loose stools and abdominal cramps but no hematochezia, melena, vomiting, or abnormal menses. Vital signs are within normal limits. Conjunctival pallor is present. The abdomen is mildly distended but nontender. Laboratory evaluation reveals anemia and a low ferritin level. Fecal occult blood testing is negative. An upper endoscopy is performed and reveals no visible abnormalities of the stomach or duodenum, although biopsies of the duodenum are significant for intraepithelial lymphocytosis. Which of the following is the most likely cause of this patient's condition?
Celiac disease | |
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This patient with loose stools and crampy abdominal pain has celiac disease, an autoimmune disorder of the small intestine triggered by dietary gluten. Besides intestinal symptoms, celiac disease commonly causes nutrient malabsorption that leads to weight loss, steatorrhea (ie, greasy, malodorous stools), and deficiency of iron (eg, anemia, low serum ferritin) and vitamin D (eg, loss of bone density).
Initial testing for celiac disease typically includes an anti-tissue transglutaminase IgA assay. The diagnosis is confirmed with duodenal biopsy. The earliest histologic finding is intraepithelial lymphocytosis; crypt hyperplasia and villous blunting develop later as the disorder progresses.
Celiac disease occurs almost exclusively (>99%) in individuals with an HLA-DQ2 or -DQ8 serotype. These variants must be present on antigen-presenting cells for recognition of deamidated gliadin (a breakdown product of gluten) and induction of the T-cell–mediated response.
(Choice A) Lactose intolerance is caused by a deficiency in lactase, an enzyme located on the small intestine brush border. Although diarrhea is common, lactose intolerance does not cause iron deficiency anemia or intraepithelial lymphocytosis.
(Choices B and E) Both Helicobacter pylori and nonsteroidal anti-inflammatory drugs can cause iron deficiency due to chronic upper gastrointestinal blood loss. However, they typically cause gastritis, duodenitis, or peptic ulcer disease, none of which was identified during this patient's endoscopy. Diarrhea, duodenal lymphocytosis, and a negative fecal occult blood test make celiac disease more likely.
(Choice D) Irritable bowel syndrome is a disorder of bowel motility that causes abdominal pain associated with defecation, as well as diarrhea and/or constipation. It does not cause iron deficiency anemia or duodenal intraepithelial lymphocytosis.
Educational objective:
Celiac disease is an autoimmune disorder triggered by dietary gluten that develops almost exclusively in patients with HLA-DQ2 or -DQ8 serotypes. It often causes diarrhea and malabsorption (eg, iron deficiency anemia). The earliest histologic finding is duodenal intraepithelial lymphocytosis; crypt hyperplasia and villous blunting develop later.