A 30-year-old man presents with chronic diarrhea, abdominal pain, and weight loss. He is suspected to have inflammatory bowel disease, but the colonoscopy and biopsy are unremarkable. What could be the diagnosis?
Though these symptoms initially suggest inflammatory bowel disease, a negative colonoscopy and biopsy suggest another cause. Celiac disease could be a possible diagnosis, which is an autoimmune disorder triggered by gluten ingestion that leads to damage of the small intestine, causing symptoms like diarrhea, abdominal pain, and weight loss. Serologic testing for anti-tissue transglutaminase antibodies followed by a small bowel biopsy could confirm this diagnosis.