What is the hydrogen breath test?
The hydrogen breath test is a test that uses the measurement of hydrogen in the breath to diagnose several conditions that cause gastrointestinal symptoms. In man, only bacteria, specifically, anaerobic bacteria in the colon–are capable of producing hydrogen. The bacteria produce hydrogen when they are exposed to unabsorbed food, particularly sugars and carbohydrates. Although limited hydrogen is produced from the small amounts of unabsorbed food that normally reach the colon, large amounts of hydrogen may be produced when there is a problem with the digestion or absorption of food in the small intestine that allows more unabsorbed food to reach the colon. Large amounts of hydrogen also may be produced when the colonic bacteria move back into the small intestine, a condition called bacterial overgrowth of the small bowel. In this latter instance, the bacteria are exposed to unabsorbed food that has not had a chance to completely traverse the small intestine to be fully digested and absorbed. Some of the hydrogen produced by the bacteria is absorbed into the blood flowing through the wall of the small intestine and colon. The hydrogen-containing blood travels to the lungs where the hydrogen is released and exhaled in the breath where it can be measured.
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 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 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.
What can I expect from a Hydrogen Breath Test?
This test requires that you drink a solution of lactulose, lactose or fructose in water. Lactose is the sugar found in milk and is normally broken down in the small bowel. Lactulose is a synthetic sugar composed by fructose and galactose that is not absorbed and that will be broken down by bacteria if present in the small bowel with hydrogen as a by-product. Fructose is a simple sugar found in many foods such as honey, tree fruits and root vegetables.
After drinking the solution, you will be asked to breathe into a small handheld device that will record Hydrogen parts per million in your breath. Breath samples are obtained every 15 to 20 minutes.
The breath sample will be analyzed for hydrogen content to determine if you are able to properly break down the lactose or fructose, or if you have bacteria overgrowth (Lactulose breath test). The test lasts approximately two and a half hours and is performed in the Celiac Disease Center at Columbia University.
When should a breath test be indicated / recommended / prescribed?
Usually a breath test is indicated when there is a suspicion of sugar malabsorption, bacterial overgrowth or abnormal transit time. Some of the symptoms associated with these conditions are abdominal bloating, diarrhea and abdominal pain.