• Increased active anion secretion
  • Decreased absorption of H2O and lytes
    • Inhibited or defective absorption
    • Luminal presence of osmotically active agents
    • Increased propulsive motor activity causing decreased contact time
    • Decreased absorptive surface area


  • Etiology: travel, homosexual contact, outbreaks, foods ingested, extraintestinal manifestations of IBD, antibiotics, steatorrhea, weight loss, immunosppressed, laxative use, malignancy history
  • Manifestation of mucosal inflammation: fever, blood in stool, abdo pain between BM, tenesmus
  • Severity: frequency, duration

Physical exam

  • General appearance
  • Vitals
  • Volume status
  • Abdominal exam
  • Rectal exam



  • Stool WBC
  • Culture/sensitivity
  • O&P
  • Flexible sigmoidoscopy
  • C.difficile toxin

Differential diagnosis

  • Infectious
    • Viral (i.e. Norwalk, Rotavirus)
    • Bacterial Infectious, Bacterial Toxic
    • Giardia
    • Food poisoning (Salmonella, spont resolution within 24-48 hr)
    • Traveller’s (E. coli, use bismuth subsalicylate, empiric quinolone)
  • Drugs: laxatives, antacids, antibiotics can cause acute and chronic diarrhea. Pseudo-membranous colitis 2° to Clostridium difficile
  • Functional/Irritable colon
  • Impaction
  • Malabsorption: lactose intolerance, celiac disease, pancreatic insufficiency, immunodeficiency
  • Inflammatory Bowel Disease
  • Endocrine: diabetes, hyperthyroidism
  • Tumor: partial obstruction or secretions
  • Immune Deficiency


  • Replace electrolyte and fluids
  • Antimotility agents: loperamide (contraindicated in mucosal inflammation)
  • Absorbants: Kaopectate (absorb intestinal toxins/micro-organisms, and by coating intestinal mucosa)
  • Bismuth subsalicylate
  • Antibiotics

Chronic diarrhea

  • Inflammatory: Ulcerative colitis, Crohn’s, malignancy: lymphoma, adenocarcinoma (fever, hematochezia, pain, weight loss)
  • Osmotic: ingestion, lactose intolerance, medications, laxatives (decreased stool volume with fasting)
  • Maldigestion/malabsorption: pancreatic insufficiency, bile salt deficiency, celiac sprue, Whipple’s disease, bowel resection (decreased stool volume with fasting)
  • Secretory: bacterial enterotoxins, secretagogues, VIP, gastrin, carcinoid
  • Functional

Stool osmotic gap = OSMstool(usually 290) – [2 x (Nastool + Kstool)]

  • increased in osmotic diarrhea (>50) and secretory diarrhes (<50)

Vitamin K dependent clotting factors: 2, 7, 9, 10, protein C, protein S (TNTS)

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