Causes of Chronic Diarrhea

Diarrhea lasting for more than 4 weeks is considered as chronic diarrhea and need to be evaluated to exclude serious underlying pathology. Chronic diarrhea is one of the common cause of bad health state of many persons. In contrast to acute diarrhea, most of the causes of chronic diarrhea are generally noninfectious. The following are the causes of chronic diarrhea:

• Secretory causes of chronic diarrhea: Excessive use of stimulant laxatives, chronic ingestion of alcohol, certain drugs and toxins, endogenous laxatives like bile acids, idiopathic secretory diarrhea; bowel resection, disease, or fistula (reduced absorption), certain bacterial infections, Addison’s disease, congenital electrolyte absorption defects, partial bowel obstruction which may be due to fecal impaction, hormone-producing tumors (carcinoid, medullary cancer of thyroid, mastocytosis, gastrinoma, colorectal villous adenoma) are the secretory causes of chronic diarrhea.
• Inflammatory causes of chronic diarrhea: Inflammatory bowel diseases (Crohn’s, chronic ulcerative colitis), infections (invasive bacteria, viruses, and parasites, Brainerd diarrhea), gastrointestinal cancers, injury due to radiation, lymphocytic and collagenous colitis, Immune-related mucosal disease (1° or 2° immunodeficiencies, food allergy, eosinophilic gastroenteritis, graft-vs-host disease) etc. are the causes of chronic diarrhea due to inflammatory cause.
• Osmotic causes of chronic diarrhea: Lactase and other disaccharide digesting enzyme deficiencies, excessive use of osmotic laxatives (containing Mg²⁺, PO₄^–3, SO₄^–2), nonabsorbable carbohydrates like sorbitol, lactulose, polyethylene glycol etc. are osmotic causes of chronic diarrhea.
• Steatorrheal causes of chronic diarrhea: Post-mucosal obstruction, intraluminal mal-digestion (pancreatic exocrine insufficiency, bacterial overgrowth, bariatric surgery, liver disease etc.), mucosal mal-absorption like celiac sprue, Whipple’s disease, certain infections, abetalipoproteinemia, ischemia of intestine etc. are the steatorrheal causes of chronic diarrhea.
• Dysmotile causes of chronic diarrhea: Irritable bowel syndrome, hyperthyroidism, certain drugs especially prokinetic agents, postvagotomy, visceral neuromyopathies etc. are the causes of dysmotile of chronic diarrhea.
• Iatrogenic (hospital acquired) causes of chronic diarrhea: Cholecystectomy (surgical removal of gall bladder), resection of ileum, Bariatric surgery, vagotomy, fundoplication etc. are the Iatrogenic causes of chronic diarrhea.
• Factitial causes of chronic diarrhea: Eating disorders, Munchausen are the cause of Factitial chronic diarrhea.