The SIBO (small intestinal bowel overgrowth) test is an at home breath test that is used to identify if there is an abnormally high level of bacteria in the small intestines. Common causes of SIBO include a standard American diet, prior gallbladder removal, bowel structural abnormalities, diabetes, aging, stress, celiac disease, hypothyroidism, chronic GI infection such as H. Pylori, and medications such as proton-pump inhibitors. SIBO presents with IBS (irritable bowel syndrome) type symptoms.