Chronic, Noninfectious Diarrhea: A Review

Area of Science:

• Gastroenterology
• Internal Medicine

Background:

• Chronic diarrhea, defined as lasting over 4 weeks, affects 6-7% of US adults, with over 90% having noninfectious causes.
• Common noninfectious etiologies include irritable bowel syndrome with diarrhea (IBS-D) and functional diarrhea, distinguished by abdominal pain and stool characteristics.

Purpose of the Study:

• To outline the common causes, diagnostic approaches, and therapeutic strategies for chronic noninfectious diarrhea.
• To emphasize the importance of differentiating between various causes for targeted treatment.

Main Methods:

• Review of common causes: IBS-D, functional diarrhea, celiac disease, small intestinal bacterial overgrowth, bile acid diarrhea, and microscopic colitis.
• Diagnostic considerations include serological testing for celiac disease, fecal calprotectin for inflammatory bowel disease, and colonoscopy with biopsies for microscopic colitis.
• Evaluation for colorectal cancer is recommended in specific patient groups.

Main Results:

• IBS-D and functional diarrhea are the most frequent diagnoses when specific organic causes are not identified.
• Microscopic colitis is found in 13% of chronic diarrhea cases upon colon biopsy.
• Therapeutic interventions, including lifestyle modifications and medications, can improve symptoms in 50-80% of patients.

Conclusions:

• Key differential diagnoses for chronic diarrhea include IBS-D, functional diarrhea, celiac disease, inflammatory bowel disease, and microscopic colitis.
• A systematic diagnostic approach is crucial for effective management.
• Empiric treatment with lifestyle adjustments, dietary changes, or medications can significantly alleviate symptoms.