chronic diarrhea

• related: GI

Testing

• CBC, iron studies, TSH, fecal calprotectin
• celiac disease, C.diff
• small intestine evaluation: small bowel xray, CT enterography, MR enterography for diverticular disease, inflammation, strictures
• upper endoscopy: when small bowel mucosal disease suspected
• capsule endoscopy: visualize small bowel but no sampling
• colonoscopy: evaluate malignancy, IBD, microscopic colitis
• stool studies:
  • fecal weight, fecal electrolytes, pH, calprotectin,
  • blood/leukocytes: inflammatory cause
  • fecal fat: 72 hour collection confirms steatorrhea
  • reduced fecal elastase: exocrine pancreatic function
  • laxative screen: laxative abuse
• osmotic gap: 290 – (2 × [stool sodium + stool potassium])

  • 50: osmotic diarrhea

  • < 50: secretory diarrhea