Overview
Clinical Meaning
Irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD) share overlapping GI symptoms but differ fundamentally in pathophysiology, diagnosis, and management.
Irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD) share overlapping GI symptoms but differ fundamentally in pathophysiology, diagnosis, and management. IBS is a functional GI disorder characterized by chronic abdominal pain associated with altered bowel habits WITHOUT identifiable structural or biochemical abnormalities. It is a disorder of gut-brain interaction involving visceral hypersensitivity (lowered pain threshold to luminal distension), altered GI motility, and psychosocial factors. IBD (Crohn disease and ulcerative colitis) is an immune-mediated chronic inflammatory condition with identifiable mucosal damage, tissue destruction, and systemic inflammation. Key distinguishing features: IBS has NO alarm features (no weight loss, no GI bleeding, no nocturnal symptoms, no fever, no anemia, NORMAL inflammatory markers, NORMAL calprotectin); IBD has alarm features (weight loss, bloody stools, nocturnal diarrhea, fever, anemia, elevated CRP/ESR, elevated fecal calprotectin). Fecal calprotectin is the single most useful non-invasive test for distinguishing IBS from IBD: elevated in IBD (reflects neutrophilic intestinal inflammation), NORMAL in IBS. IBS is diagnosed by Rome IV criteria (clinical criteria — no specific diagnostic test), while IBD requires endoscopy with biopsy for definitive diagnosis. IBS prevalence is 10-15%...