Systems and methods have been developed for implementation of a portable SIBO testing system for convenient sampling of intestinal gases exhaled from a patient's breath. These devices may be in the form of a hand held meter that would integrate with a smartphone or other device with an application that can record data relating to food consumed by a user. Various technologies may be utilized to measure the levels of gases exhaled by a user, which may include (1) sorbent based technology and (2) membrane based technology. In some examples, the system will determine an indication of whether a patient has SIBO by adjusting a change in exhaled hydrogen concentration by a methane level exhaled by a patient.