This test is used to help diagnose Small Intestinal Bacterial Overgrowth (SIBO) and Intestinal Methanogen Overgrowth (IMO). When bacteria normally found in the large intestine become present in the small intestine, the digestive system may produce excessive hydrogen and/or methane gas, which can cause many gastrointestinal symptoms such as bloating, diarrhea, and constipation. This test comes with a GLUCOSE substrate.