72-hour fecal fat quantitation or Sudan staining of stool if steatorrhea is suspected. Breath hydrogen test for lactase deficiency. Can also check for reducing substances in stool or therapeutic trial of lactose-free diet. Small bowel culture for bacterial overgrowth. Bring stool pH to 8.0.
Urine tests are available to detect aloes, senna alkaloids, and bisacodyl.
Sigmoidoscopy should be done to detect inflammation of the colon or rectum, neoplasms, and parasites. Plain abdominal radiography and barium studies of the upper GI tract, small intestine, and colon. Treatment Should be directed toward underlying cause of the chronic diarrhea. Restrictions should be done systematically so that if symptoms improve, the restricted factor can be identified and removed permanently from the diet. Increase dietary or supplemental fiber.