Evaluation for Chronic Diarrhea

Initial History and Risk Assessment

• The American Gastroenterological Association recommends beginning the evaluation of chronic diarrhea with a detailed history focusing on alarm features, such as blood in stool, unintentional weight loss, nocturnal symptoms, and duration less than 3 months, followed by first-line laboratory testing including complete blood count, C-reactive protein, IgA tissue transglutaminase with total IgA level, and stool testing for Giardia 1, 2, 3
• Symptoms less than 3 months duration or nocturnal diarrhea suggest organic disease rather than functional disorders, according to the British Society of Gastroenterology 2, 3
• Alarm features such as blood in stool, unintentional weight loss, fever, or recent change in bowel habit warrant urgent evaluation, as recommended by the European Society of Gastrointestinal Endoscopy 2, 3
• A surgical history of terminal ileal resection, cholecystectomy, or abdominal radiotherapy are strong risk factors for bile acid diarrhea, as noted by the American College of Gastroenterology 4, 5, 6
• Recent travel to or immigration from high-risk areas changes the testing approach, according to the Centers for Disease Control and Prevention 1, 7

First-Line Laboratory Testing

• The American Gastroenterological Association recommends celiac disease screening with IgA tissue transglutaminase plus total IgA level to detect IgA deficiency, with a sensitivity and specificity exceeding 90% when using thresholds of 7-15 AU/mL 1, 7
• Giardia testing using Giardia antigen test or PCR has sensitivity and specificity greater than 95%, as recommended by the Infectious Diseases Society of America 1, 7
• Complete blood count and C-reactive protein are used to screen for inflammatory conditions and anemia, according to the British Society of Gastroenterology 2

Bile Acid Diarrhea Assessment

• The American College of Gastroenterology recommends SeHCAT testing as the preferred diagnostic test for bile acid diarrhea, if available, for patients with specific risk factors such as terminal ileal resection, cholecystectomy, or radiotherapy 4, 5, 6
• Serum C4 assay can be used as an alternative where SeHCAT is unavailable, as noted by the European Society of Gastrointestinal Endoscopy 4, 5
• Empiric trial of bile acid sequestrants may be considered when testing is unavailable, though formal diagnosis is preferred, according to the American Gastroenterological Association 1, 4, 5

Endoscopic Evaluation

• The American Society for Gastrointestinal Endoscopy recommends colonoscopy with biopsies when inflammatory markers are elevated, alarm features are present, or initial testing is unrevealing but symptoms persist and impair quality of life 2, 3
• Upper endoscopy with duodenal biopsies should be performed when celiac serology is positive to confirm the diagnosis, as recommended by the North American Society for Pediatric Gastroenterology, Hepatology and Nutrition 1, 7

Common Pitfalls to Avoid

• Failing to test for celiac disease and Giardia in all patients with chronic diarrhea, regardless of symptom presentation, is a common pitfall, according to the American Gastroenterological Association 1, 7
• Ordering broad ova and parasite panels in patients without travel history has extremely low yield, as noted by the Infectious Diseases Society of America 1, 7
• Neglecting medication review as a potential cause, particularly proton pump inhibitors, antibiotics, and metformin, is a common mistake, according to the British Society of Gastroenterology 2
• Missing IgA deficiency when interpreting celiac serology causes false-negative IgA-tTG results, as recommended by the European Society of Gastrointestinal Endoscopy 1, 7
• Assuming functional diarrhea based on Rome IV criteria alone is not reliable, as these criteria have only 52-74% specificity and do not reliably exclude IBD, microscopic colitis, or bile acid diarrhea, according to the American College of Gastroenterology 2, 3
• Overlooking bile acid diarrhea in patients with prior cholecystectomy or ileal resection is a common pitfall, as noted by the American College of Gastroenterology 4, 5, 6

Chronic Diarrhea Management

Diagnostic Approach

• The European Society of Gastrointestinal Endoscopy recommends a detailed history to distinguish organic from functional causes of chronic diarrhea, including blood tests and stool tests for inflammation, in patients with chronic diarrhea 8
• Chronic diarrhea is defined as abnormal passage of ≥3 loose stools per day for more than 4 weeks, according to the American Gastroenterological Association 9
• Initial assessment should include serological testing for celiac disease, as recommended by the European Society of Gastrointestinal Endoscopy 8

Categorization of Chronic Diarrhea

• Chronic diarrhea can be categorized into three main types: watery diarrhea, fatty diarrhea (malabsorption), and inflammatory diarrhea, as classified by the American Gastroenterological Association 10
• Watery diarrhea can be further categorized into functional, secretory, and osmotic types, with lactose intolerance and medication side effects being common causes of osmotic diarrhea, according to the European Society of Gastrointestinal Endoscopy 11

Treatment Based on Specific Causes

• The American Gastroenterological Association recommends cholestyramine as initial therapy for bile acid diarrhea, with alternate bile acid sequestrants when tolerability is an issue 12
• The European Society of Gastrointestinal Endoscopy recommends specific disease-modifying therapies for inflammatory bowel disease, based on disease type and severity 11
• The American College of Gastroenterology recommends a strict gluten-free diet for the treatment of celiac disease, as confirmed by serological testing and duodenal biopsies 8
• The European Society of Gastrointestinal Endoscopy recommends an empirical trial of antibiotics for the treatment of small bowel bacterial overgrowth, rather than routine hydrogen or methane breath testing 11
• The American Gastroenterological Association recommends medication review and discontinuation of offending agents when possible, for the treatment of medication-induced diarrhea 8
• The European Society of Gastrointestinal Endoscopy recommends dietary lactose restriction or lactase enzyme supplements for the treatment of lactose intolerance, with hydrogen breath testing to confirm diagnosis if available 8

Symptomatic Management

• The American Gastroenterological Association recommends dietary modifications to eliminate potential triggers, such as caffeine, alcohol, sorbitol, and fructose, for symptomatic relief of chronic diarrhea 8
• The European Society of Gastrointestinal Endoscopy recommends cholestyramine for bile acid diarrhea, as a symptomatic treatment option 10

Common Pitfalls to Avoid

• The American Gastroenterological Association recommends distinguishing between functional disorders and organic disease, to avoid failing to diagnose underlying conditions 9
• The European Society of Gastrointestinal Endoscopy recommends reviewing medications as potential causes of chronic diarrhea, to avoid neglecting this common cause 8

Chronic Diarrhea Evaluation and Management

Initial History and Risk Stratification

• A family history of inflammatory bowel disease, celiac disease, or colorectal cancer increases pretest probability, according to the American Gastroenterological Association 13
• Bulky, pale, malodorous stools suggest malabsorption/steatorrhea, while liquid loose stools with blood or mucus suggest colonic/inflammatory etiology, as noted by the European Society of Gastrointestinal Endoscopy 13
• Symptoms <3 months duration suggest organic rather than functional disease, as reported by the National Institute of Diabetes and Digestive and Kidney Diseases 13

Endoscopic Evaluation

• Aim for >90% cecal intubation rate with terminal ileal intubation during colonoscopy, as recommended by the American College of Gastroenterology 14

Diarrhea Type and Targeted Testing

• Laxative abuse can be diagnosed with stool/urine testing for laxatives, according to the World Gastroenterology Organisation 13