Chronic diarrhea

DDx

Common

• Irritable bowel syndrome, lactase deficiency, parasites, caffeine, alcohol, laxative abuse

• Lactase deficiency
• Medications: antacids, lactulose, sorbitol, Olestra
• Factitious: magnesium-containing antacids or laxatives

• Hormonal: Zollinger-Ellison syndrome (gastrinoma), carcinoid, VIPoma, medullary thyroid carcinoma
• Laxative abuse: phenolphthalein, cascara, senna
• Villous adenoma
• Medications

• Inflammatory bowel disease
• Microscopic colitis (lymphocytic or collagenous)
• Cancer with obstruction and pseudodiarrhea
• Radiation colitis

• Small bowel: celiac sprue, Whipple's disease, tropical sprue, eosinophilic gastroenteritis, small bowel resection, Crohn's disease
• Lymphatic obstruction: lymphoma, carcinoid, tuberculosis, Mycobacterium avium complex (MAC), Kaposi's sarcoma, sarcoidosis, retroperitoneal fibrosis
• Pancreatic insufficiency: chronic pancreatitis, cystic fibrosis, pancreatic cancer
• Bacterial overgrowth, eg, diabetes
• Reduced bile salts: ileal resection, Crohn's disease, postcholecystectomy

• Irritable bowel syndrome
• Postsurgical: vagotomy, partial gastrectomy, blind loop with bacterial overgrowth
• Systemic disease: diabetes mellitus, hyperthyroidism, scleroderma
• Caffeine or alcohol use

• Parasites: giardiasis, amebiasis, strongyloidiasis

• Ischemic colitis
• Adrenal insufficiency