Hydrogen breath testing is used in the diagnosis of three conditions.
The first is a condition in which dietary sugars are not digested normally. The most common sugar that is poorly digested is lactose, the sugar in milk. Individuals who are unable to properly digest lactose are referred to as lactose intolerant. Testing also may be used to diagnose problems with the digestion of other sugars such as sucrose, fructose and sorbitol.
The second condition for which hydrogen breath testing is used is for diagnosing bacterial overgrowth of the small bowel, a condition in which larger-than-normal numbers of colonic bacteria are present in the small intestine.
The third condition for which hydrogen breath testing is used is for diagnosing rapid passage of food through the small intestine. All three of these conditions may cause abdominal pain, abdominal bloating and distention, flatulence (passing gas in large amounts), and diarrhea.