Symptoms suggestive of organic disease:

– Symptom onset >50 years

– Progressively worsening symptoms

– Unexplained weight loss or loss of appetite

– Nocturnal diarrhea

– Family history of colon cancer, celiac disease, or IBD

– Blood in stool (melena)

– Unexplained iron deficiency anemia

– Abdominal mass

– Ascites

– Elevated WBC count

– Fever

– Recent change in symptoms

Commonly used tests:

– CBC

– tTG IgA (to exclude celiac disease), duodenal biopsy

– CRP and fecal calprotectin (if suspecting IBD; not used routinely)

– Colonoscopy (in GI bleeding, unexplained weight loss, family history of colon cancer, and/or abdominal mass, or age >50 years). Consider random biopsies in diarrhea to exclude microscopic colitis

– Hydrogen breath test (to exclude SIBO [glucose substrate] or fructose/lactose intolerance [glucose or lactose substrate]; not to be used routinely)

– Plain film of abdomen (may be useful to exclude fecal loading)

– Motility test (may be useful to identify origin of constipation)