Evaluation of Patients with IBS
1- Food history including type and amount
2- Routine blood tests; CBC, complete metabolic panel, thyroid function test, ESR, CRP, Helicobacter pylori antibody
3- Lactose tolerance test or lactose breath test in most if not all
4- Lactulose breath test to evaluate for SIBO in selected cases
5- Fructose breath test in selected patients.
6- Celiac Sprue blood test at least 2, TTGAB and gliadin antibody in selected cases
7- Stool guiac for occult blood
8- Colonoscopy in patients over 50 and those with Alarm symptoms.
Colonoscopy even if negative can identify hemorrhoids, polyps, diverticulosis, circular muscle hypertrophy, angiodysplasia, and microscopic colitis ( 5% of IBS diarrhea).