Lecture on Diarrhea: Causes, Diagnosis, and Types

Jun 19, 2024

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Diarrhea: Causes, Diagnosis, and Types

Definition

  • Diarrhea: Stools occurring more than three times a day, looser than usual
  • Diagnostic measure: More than 200 grams of stools in 24 hours

Causes of Diarrhea

Acute Causes

  • Lasts less than 4 weeks
  • Often caused by infections (viral or toxin-mediated)
  • Typically resolves spontaneously

Chronic Causes

  • Lasts more than 4 weeks
  • Divided into organic and functional causes

Organic Causes

  • Detectable through testing
  • Examples:
    • Celiac disease
    • Inflammatory bowel disease (ulcerative colitis, Crohn's disease)
    • Bacterial and parasitic infections
    • Pancreatic insufficiency
    • Intestinal neoplasms

Functional Causes

  • Cannot be quantified through testing
  • Examples:
    • Irritable bowel syndrome (IBS)
    • Lactose intolerance
    • Food allergy
    • Drug or alcohol abuse

Distinguishing Functional from Organic Diarrhea

Organic Diarrhea

  • Duration: Weeks to years
  • Larger volume
  • Blood presence: Yes
  • Timing: No specific pattern, may wake the patient at night
  • Associated with extra symptoms: Fever, arthritis, skin lesions
  • Weight loss: Yes
  • Cramping pain: Often

Functional Diarrhea

  • Duration: Over 6 months
  • Smaller volume
  • Blood presence: No
  • Timing: Typically mornings, doesn't wake patient
  • Associated with stress: Yes
  • Extra symptoms: Rare
  • Weight loss: Only with anorexia
  • Cramping pain: Less frequent

Small vs. Large Bowel Diarrhea

Small Bowel Diarrhea

  • Higher volume, lower frequency
  • Color: Yellow or gray

Large Bowel Diarrhea

  • Lower volume, higher frequency
  • Blood and mucus: Common

Diagnostic Follow-Up

  • Follow-up based on findings:
    • Esophageal duodenoscopy
    • Colonoscopy
    • Biopsies

Types of Diarrhea (Pathophysiology)

Osmotic Diarrhea

  • Increased concentration of osmotically active solutes in the lumen
  • Causes: Malabsorptive diseases (e.g., celiac disease), osmotic laxatives
  • Resolves with fasting
  • Osmotic gap: > 100 mOsm/kg

Secretory Diarrhea

  • Active secretion of water and electrolytes via adenylate/guanylate cyclase activation
  • Causes: Bacterial endotoxins (e.g., E. coli, cholera)
  • No response to fasting
  • No osmotic gap

Inflammatory Diarrhea

  • Due to intestinal mucosa inflammation
  • Often features blood and mucus
  • No response to fasting

Diarrhea of Altered Motility

  • Increase in peristalsis
  • Less time for reabsorption