Hydrogen Breath Test Diagnosis, Procedure, Normal and Positive Ranges (original) (raw)
What is the hydrogen breath test?
Hydrogen breath test is used to diagnose lactose intolerance and small intestinal bacterial overgrowth. SOURCE: iStock / Getty Images
The hydrogen breath test is used to help diagnose two digestive conditions, lactose intolerance/malabsorption and small intestinal bacterial overgrowth (SIBO).
Lactose is a sugar found in dairy products. When milk, cheese, yogurt, ice cream, or other lactose containing foods are consumed, lactase, an enzyme found in the lining of the small intestine, helps convert the lactose into glucose and galactose. These two sugars can be absorbed into the body and used for energy. However, if lactase enzyme is missing, lactose is not absorbed and passes into the colon (large intestine), where bacteria ferment the lactose into hydrogen, methane, and carbon dioxide. These get absorbed into the bloodstream and then exhaled from the lungs into the air. The symptoms of lactose intolerance are due to the excess gas that is produced and include crampy abdominal pain, flatulence, and loose stools.
SIBO occurs when excessive amounts of bacteria migrate into the small intestine from the colon. This upsets the normal small intestine flora and hinders absorption of vitamins, minerals, fats, and sugars. The bacteria cause excessive production of hydrogen, methane, and carbon dioxide that can lead to abdominal bloating, flatulence, and diarrhea. Because of the malabsorption of nutrients, weight loss and malnutrition may occur with associated adverse effects on many body systems.
What does a hydrogen breath test diagnose?
The hydrogen breath test is a way to help with the diagnosis of lactose intolerance and small intestinal bacterial overgrowth. The test by itself does not make the diagnosis, but needs to be interpreted based on the patient’s symptoms, physical exam, and other findings.
Other tests are available to help diagnose lactose intolerance and SIBO. The hydrogen breath test is often ordered initially because it is noninvasive.
How does a hydrogen breath test work?
Hydrogen is not normally produced in the body. When it is, the lungs remove it from the body with exhaled air. The hydrogen concentration in this exhaled air can be measured. On occasion, methane can also be measured in the exhaled air.
How do you prepare for a hydrogen breath test?
It takes a few weeks to prepare for the test. The intestine needs to be at its baseline to make certain the results are valid.
- One month up until the test, antibiotics and probiotics need to be avoided because they can alter the bacteria counts in the intestine.
- One week up until the test, substances and medications that affect the motility or movement of the intestine need to be avoided. These include laxatives, fiber supplements, and antacids. They can increase how quickly the contents of the intestines move and affect the results of the test.
- One day up until the test, complex carbohydrates in your diet need to be avoided.
- 8-12 hours up until the test, the patient will need to fast and not eat or drink any foods or liquids. There should also be no smoking or exercise. Smoking can increase hydrogen levels in the breath. Exercising can increase the breathing rate and decrease hydrogen levels.
What is the procedure for a hydrogen breath test?
For lactose intolerance:
The hydrogen breath test will take up to five hours. It takes about 90 minutes for the solution to pass through the stomach and small intestine into the colon. If there is lactase deficiency, the lactose solution will enter the colon unchanged and then the colonic bacteria will ferment it into hydrogen and methane.
- First, the patient blows into a breathalyzer machine, usually through a tube with a bag attached. This allows a baseline measurement.
- The patient then drinks a solution containing lactose.
- Every 15-30 minutes, over the next few hours, the patient will blow into the breathalyzer and the hydrogen and methane concentrations will be measured.
- The patient will also be monitored for symptoms of lactose intolerance if present.
For SIBO:
The hydrogen breath test will only take 60-90 minutes. The sugar solution contains lactulose which cannot be metabolized by the body. If there are excess bacteria present in the small intestine, the lactulose will be fermented relatively quickly to form hydrogen and methane. Once the solution passes into the colon, it is expected that gasses would be produced, so any measurements of the gasses after the 90 minutes are not helpful.
- The baseline breaths into the breathalyzer are obtained.
- The patient will drink a lactulose and glucose solution.
- The patient will blow into the breathalyzer every 15-30 minutes for only a 90-minute duration.
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What do the results of a hydrogen breath test mean?
What is the normal range for a hydrogen breath test?
The normal range for hydrogen in the breath is less than 16 parts per million (ppm).
What is a positive hydrogen breath test?
Lactose intolerance/malabsorption:
- A hydrogen level greater than 20 ppm above baseline is positive for lactose intolerance. The test may last 3-5 hours.
- The patient needs to be assessed during the test. If the patient develops symptoms of cramping and bloating, the diagnosis can be confirmed and treatment may be helpful. If no symptoms occur, even if the test is positive, further testing will be needed because it is unlikely that lactose malabsorption is the cause of the patient’s initial complaints. Treatment for lactose malabsorption may not be helpful.
SIBO:
- A hydrogen level greater than 20 ppm above baseline within 90 minutes is a positive test for SIBO. The time frame is important because elevated levels longer than 90 minutes are due to fermentation of bacteria in the colon and in the small intestine.
- Methane levels that are greater than 10 ppm are considered methane positive.
What are the side effects of hydrogen breath testing?
The side effects of the test are due to drinking the solution, which can bring on the symptoms associated with lactose intolerance or SIBO.
Health News
Medically Reviewed on 9/25/2024
References
De Geyter C, Van de Maele K, et al. Hydrogen and Methane Breath Test in the Diagnosis of Lactose Intolerance. Nutrients. 2021 Sep 18;13(9):3261.
Rezaie A, Buresi M, et al. Hydrogen and Methane-Based Breath Testing in Gastrointestinal Disorders: The North American Consensus. Am J Gastroenterol. 2017 May;112(5):775-784.
Keller J, Hammer HF, et al. European 13C-breath test group. European guideline on indications, performance and clinical impact of 13 C-breath tests in adult and pediatric patients: An EAGEN, ESNM, and ESPGHAN consensus, supported by EPC. United European Gastroenterol J. 2021 Jun;9(5):598-625.
Hammer HF, Fox MR, et al. European H2-CH4-breath test group. European guideline on indications, performance, and clinical impact of hydrogen and methane breath tests in adult and pediatric patients: European Association for Gastroenterology, Endoscopy and Nutrition, European Society of Neurogastroenterology and Motility, and European Society for Paediatric Gastroenterology Hepatology and Nutrition consensus. United European Gastroenterol J. 2022 Feb;10(1):15-40.