chronic diarrhea

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