Page reviewed by: Mr Nicholas Boyle BM MS FRCS 03/07/20
Breath tests are most commonly used to diagnose small intestinal bacterial overgrowth (SIBO) and malabsorption of sugars such as lactose or fructose. Malabsorption is the imperfect absorption of food material by the small intestine. These conditions can cause similar symptoms to reflux and can occur independently or co-exist with GORD (Gastro Oesophageal Reflux Disease). Identifying their existence is important as if they go unrecognised patients may undergo unnecessary surgery, or, if surgery is performed, they may find that it works poorly or that they experience side effects. For instance, if a patient has bloating caused by SIBO, a Nissen fundoplication procedure may worsen this symptom.
A sample of the patient’s breath is analysed. The exhaled breath is tested to measure the production of hydrogen and methane gases by gut bacteria.
In the case of SIBO, fermentation of food by bacteria in the small bowel can inhibit normal absorption, produce gas, and increase the number of substances called short chain fatty acids in the gut. This can lead to symptoms of bloating, nausea and cramping as well as altered bowel habit. Performing a breath test allows diagnosis based on measurement of both hydrogen and methane. This means better characterisation of gut bacteria, which enables tailored treatment regimens based on accurate diagnosis.