How do I manage a patient with chronic diarrhea?

Management of Chronic Diarrhea: A Systematic Approach

The management of chronic diarrhea requires a structured diagnostic approach followed by targeted treatment based on the underlying cause, with initial evaluation including blood tests, stool studies, and consideration of risk factors for bile acid diarrhea such as terminal ileal resection, cholecystectomy, or abdominal radiotherapy. 1

Initial Assessment

Definition and Classification

• Chronic diarrhea is defined as the abnormal passage of ≥3 loose stools per day for more than 4 weeks 1
• Affects approximately 5% of the general population 1

Key History Elements to Assess

• Duration and pattern of symptoms (continuous vs. intermittent)
• Presence of alarm features:
  • Nocturnal diarrhea
  • Unintentional weight loss
  • Blood in stool
  • Recent onset (<3 months)
  • Family history of inflammatory bowel disease, celiac disease, or colorectal cancer 1

Risk Factors to Identify

• Terminal ileal resection
• Cholecystectomy
• Previous abdominal radiotherapy
• Previous pancreatic disease
• Systemic diseases (thyroid disorders, diabetes mellitus)
• Alcohol consumption
• Medication review 1

Diagnostic Workup

First-line Investigations (Primary Care)

1. Blood tests:

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

2. Stool studies:

   • Fecal calprotectin or lactoferrin (for inflammatory markers)
   • Stool culture and ova/parasite examination if infectious etiology suspected
   • Clostridium difficile testing if relevant 1

When to Refer to Secondary Care

• Presence of alarm features
• Symptoms severe enough to impair quality of life
• Failure to respond to initial management
• Patients over 45 years with recent change in bowel habits 1

Targeted Diagnostic Testing

For Suspected Bile Acid Diarrhea (BAD)

• Consider BAD in patients with chronic nonbloody diarrhea, especially with risk factors
• 75SeHCAT testing is recommended where available
• 7α-hydroxy-4-cholesten-3-one (C4) assay is an alternative test 1

For Suspected Inflammatory or Malabsorptive Causes

• Colonoscopy with biopsies (to evaluate for microscopic colitis, IBD)
• Upper endoscopy with duodenal biopsies if celiac disease suspected despite negative serology 1

Treatment Approach

Specific Treatments Based on Diagnosis

1. For Bile Acid Diarrhea:

   • Cholestyramine as first-line therapy
   • Alternative bile acid sequestrants if cholestyramine not tolerated 1

2. For Functional Diarrhea/IBS-D:

   • Loperamide (starting at 2mg as needed, up to 16mg daily maximum) 2
   • Rifaximin 550mg three times daily for 14 days (for IBS-D) 3

3. For Microscopic Colitis:

   • Budesonide therapy 4

4. For Small Intestinal Bacterial Overgrowth:

   • Rotating antibiotics 4

5. For Specific Conditions:

   • Celiac disease: Strict gluten-free diet
   • Inflammatory bowel disease: Appropriate anti-inflammatory therapy
   • Lactose intolerance: Lactose restriction 4, 5

Symptomatic Management When Specific Diagnosis Unclear

• Loperamide as first-line antidiarrheal (titrate dose based on response)
• Consider bile acid sequestrants (cholestyramine) if diarrhea is postprandial
• Diet modification: reduce caffeine, alcohol, sorbitol, and fructose 1, 2

Special Considerations

Elderly Patients

• Use caution with loperamide in elderly patients taking medications that can prolong QT interval
• Avoid loperamide in patients with risk factors for Torsades de Pointes 2

Hepatic Impairment

• Use loperamide with caution due to potential increased systemic exposure
• Monitor for signs of CNS toxicity 2

Follow-up and Monitoring

• If no improvement after 48 hours of symptomatic treatment, reevaluate diagnosis
• For patients on bile acid sequestrants, use the lowest effective dose
• Consider trial of intermittent, on-demand administration for maintenance therapy 1
• For persistent symptoms despite appropriate therapy, consider additional diagnostic testing or specialist referral 1

Common Pitfalls to Avoid

1. Failing to identify alarm features requiring urgent evaluation
2. Not considering medication-induced diarrhea
3. Missing bile acid diarrhea, which is frequently underdiagnosed
4. Inadequate follow-up of persistent symptoms
5. Overlooking microscopic colitis in older patients with watery diarrhea 1, 6