What is the initial workup and management for chronic diarrhea?

Initial Workup and Management for Chronic Diarrhea

The initial workup for chronic diarrhea should include blood tests, stool studies, and assessment of risk factors for bile acid diarrhea, with colonoscopy indicated for patients with alarm features. 1

Definition

• Chronic diarrhea: abnormal passage of ≥3 loose stools per day for more than 4 weeks 1
• Alternatively defined as stool weight >200g/day for at least 4 weeks 2

Initial Assessment

History and Risk Factor Assessment

• Key risk factors to identify:
  • Terminal ileal resection
  • Cholecystectomy
  • Previous abdominal radiotherapy 3, 1
  • Family history of neoplastic or inflammatory bowel disease 3
  • Medication use (antibiotics, antacids, anti-motility agents) 3
  • Travel history 3
  • Food intolerances 1

Alarm Features Requiring Urgent Evaluation

• Nocturnal diarrhea
• Unintentional weight loss
• Blood in stool
• Recent onset of symptoms
• Family history of IBD, celiac disease, or colorectal cancer 1

Initial Laboratory Tests

1. Blood tests:

   • Complete blood count
   • Basic metabolic panel
   • Thyroid function tests
   • Celiac disease serology (tissue transglutaminase antibody) 1

2. Stool studies:

   • Fecal calprotectin or lactoferrin (to assess inflammation)
   • Stool culture and ova/parasite examination
   • Clostridium difficile testing when appropriate
   • Fecal fat (if steatorrhea is suspected) 1

Diagnostic Algorithm

1. First-line investigations:

   • Laboratory tests as outlined above
   • Symptom assessment to distinguish malabsorptive from colonic/inflammatory forms 3
   • Consider open access flexible sigmoidoscopy if available 3

2. Second-line investigations based on initial findings:

   • For suspected bile acid diarrhea: SeHCAT testing or C4 assay 3, 1
   • For suspected inflammatory or neoplastic conditions: Colonoscopy with biopsies 1
   • For suspected malabsorption: Upper endoscopy with duodenal biopsies 1

3. Specialized testing for persistent undiagnosed cases:

   • Tests for small intestinal bacterial overgrowth
   • Pancreatic function tests
   • Transit studies for motility disorders 4

Initial Management

Symptomatic Treatment

• Rehydration:

  • Oral rehydration solutions for patients with significant fluid losses 3
  • Consider electrolyte replacement as needed 3, 5

• Antidiarrheal agents:

  • Loperamide: Initial dose 4 mg followed by 2 mg after each unformed stool
  • Maximum daily dose: 16 mg
  • Use with caution in elderly patients and those on medications that prolong QT interval 5

Specific Treatments Based on Diagnosis

• For bile acid diarrhea: Cholestyramine as first-line therapy 3, 1
• For inflammatory conditions: Directed anti-inflammatory therapy 1
• For functional diarrhea/IBS-D: Dietary modifications, antispasmodics, and antidiarrheals 1

Follow-up and Monitoring

• Clinical improvement should typically be observed within 48 hours of symptomatic treatment 5
• If no improvement after 48 hours, reevaluate diagnosis and consider additional testing 1
• For persistent symptoms without diagnosis after initial workup, referral to gastroenterology is warranted 6

Common Pitfalls to Avoid

• Failing to identify alarm features requiring urgent evaluation
• Not considering medication-induced diarrhea
• Missing bile acid diarrhea or microscopic colitis
• Relying solely on symptom presentation to identify bile acid diarrhea 3, 1
• Premature diagnosis of irritable bowel syndrome without adequate exclusion of organic disease 4