What is the treatment approach for chronic diarrhea?

Treatment Approach for Chronic Diarrhea

The treatment of chronic diarrhea must be directed at the underlying cause, which requires a systematic diagnostic approach before initiating specific therapy. 1 This structured approach is essential to ensure effective management and improve patient outcomes.

Initial Diagnostic Workup

First-Line Investigations

• Blood tests: Full blood count, ferritin, tissue transglutaminase/EMA, thyroid function test 1
• Stool tests: Fecal calprotectin (to exclude inflammation) 1
• Consider IBS diagnosis: After basic screening tests are negative 1

Cancer and Inflammatory Screening

• Colonoscopy: Required for patients with altered bowel habits ± rectal bleeding, especially those >45 years old 1
• Fecal immunochemical testing: For those with lower GI symptoms without rectal bleeding 1
• Fecal calprotectin: Particularly important for patients <40 years with suspected IBS 1

Diagnostic Classification

Categorize diarrhea into one of four main types to guide treatment:

1. Watery diarrhea

   • Secretory: Continues during fasting (bile acid diarrhea, microscopic colitis)
   • Osmotic: Improves with fasting (lactose intolerance, laxative abuse)
   • Functional: IBS-D, functional diarrhea

2. Fatty diarrhea (malabsorption)

   • Celiac disease, pancreatic insufficiency, small bowel bacterial overgrowth

3. Inflammatory diarrhea

   • IBD, microscopic colitis, infectious causes

4. Dysmotility-related diarrhea

   • Post-surgical, diabetic enteropathy

Targeted Testing Based on Suspected Cause

For Suspected Bile Acid Diarrhea

• SeHCAT testing or serum bile acid precursor 7α-hydroxy-4-cholesten-3-one 1
• Empiric trial of bile acid sequestrants (cholestyramine) if testing unavailable 2

For Suspected Microscopic Colitis

• Colonoscopy with biopsies of right and left colon (not rectal) 1

For Suspected Malabsorption

• Lactose hydrogen breath testing or trial of lactose withdrawal 1
• Fecal elastase for suspected pancreatic insufficiency 1
• Small bowel imaging: MR enterography or video capsule endoscopy 1

For Suspected Small Bowel Bacterial Overgrowth

• Empiric trial of antibiotics rather than breath testing 1

Treatment Approach

1. Treat Specific Causes

• Bile acid diarrhea: Cholestyramine 2
• Microscopic colitis: Budesonide
• Celiac disease: Gluten-free diet
• Small bowel bacterial overgrowth: Antibiotics (empiric trial) 1
• Pancreatic insufficiency: Pancreatic enzyme replacement
• C. difficile colitis: Oral metronidazole or vancomycin 2
• Inflammatory bowel disease: Mesalamine for mild-moderate disease, prednisolone for moderate-severe 2

2. Symptomatic Management

• Loperamide: First-line antidiarrheal for symptomatic relief 2
• Oral rehydration solutions: For fluid replacement 2
• Diet modification: Elimination of trigger foods 2
• Eluxadoline: For IBS-D when other treatments fail (caution with history of pancreatitis, alcohol abuse, cholecystitis, sphincter of Oddi dysfunction) 3

Follow-up and Monitoring

• Reassess in 3-6 weeks to evaluate treatment effectiveness 2
• Monitor for alarm features: Nocturnal diarrhea, unintentional weight loss, blood in stool 2

Common Pitfalls to Avoid

• Missing bile acid diarrhea: Common and underdiagnosed cause of chronic diarrhea 2
• Overlooking microscopic colitis: Particularly in older patients with watery diarrhea 2
• Failing to consider medication-induced diarrhea: Review all medications including OTC products 1
• Inadequate investigation of alarm symptoms: Weight loss, nocturnal symptoms, or blood in stool require thorough evaluation 2

By following this systematic approach to diagnosis and treatment, most cases of chronic diarrhea can be effectively managed, improving patient quality of life and reducing morbidity associated with prolonged symptoms.