II. Epidemiology

  1. More common in older patients (age 50 years old and older)
  2. Causes 10% of Chronic Diarrhea cases
    1. Causes 10-15% of all Secretory Diarrhea
  3. Gender
    1. Women account for most cases
  4. Age 60 years is typical (<45 years in 25% of cases)

III. Risk Factors: Medications

IV. Associated Conditions

  1. Irritable Bowel Syndrome
    1. Microscopic Colitis is present in 5-10% of Irritable Bowel Syndrome
  2. Celiac Disease

V. Symptoms

VI. Labs

  1. Stool studies without microscopic blood or mucus

VII. Associated Conditions

  1. Celiac Sprue (5% of cases)

VIII. Diagnosis: Colonoscopy findings

  1. Normal gross appearance
  2. Biopsy of transverse colon (random biopsies) confirms diagnosis with one of two histologic patterns
    1. Lymphocytic Colitis
      1. Lamina propria with lymphocytic infiltrate
    2. Collagenous Colitis
      1. Subepithelial Collagen layer increased >10mm

IX. Management

  1. Discontinue predisposing medications (esp. NSAIDs)
    1. Stop NSAIDs
    2. Stop Proton Pump Inhibitors (e.g. Omeprazole)
    3. Stop Statins
    4. Stop Selective Serotonin Reuptake Inhibitor
  2. Mild Symptoms
    1. Treat as Diarrhea predominant Irritable Bowel Syndrome
    2. Cholestyramine 4 grams qhs to 6 times daily
    3. Loperamide (Imodium) 2-4 mg four times daily prn (primarily before meals)
    4. Diphenoxylate
    5. Bismuth Subsalicylate
  3. Moderate Symptoms
    1. Budesonide AND
    2. Mild symptom management options
  4. Severe Symptoms
    1. Immunomodulators (6-mercaptopurine, Methotrexate, Azathioprine, Infliximab)

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