Chronic Diarrhea

Chronic diarrhea is the passage of loose or watery stools, with or without increased stool frequency, for longer than four weeks. That duration changes the clinical task: the goal is no longer simply to suppress a symptom but to identify the mechanism, correct physiological losses, and find a treatable cause. The stool pattern often provides the first useful classification: - Osmotic diarrhea results when an unabsorbed solute retains water in the intestinal lumen. It usually improves when the patient fasts. Lactose intolerance and poorly absorbed sugar alcohols are examples. - Secretory diarrhea results from active electrolyte secretion or impaired absorption. It continues despite fasting and may occur during sleep. Bile acid diarrhea and microscopic colitis commonly follow this pattern. - Inflammatory or exudative diarrhea reflects mucosal injury. Blood, pus, fever, anaemia, raised fecal inflammatory markers, or other systemic findings increase concern for inflammatory bowel disease, infection, or ischaemia. - Malabsorptive or steatorrheal diarrhea produces bulky, greasy, malodorous stools that may be difficult to flush. Weight loss and deficiencies of vitamins A, D, E, and K point toward impaired digestion or...