Hydrogen & Methane Breath Tests
A Hydrogen / Methane Breath Test is a painless and non-invasive test which helps to diagnose the following gastrointestinal disorders.
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Lactose Breath test for lactose intolerance (lactase deficiency)
Fructose Breath test for fructose malabsorption
Glucose Breath test for small bowel/intestinal bacterial overgrowth
Lactulose Breath test for Hydrogen production and intestinal transit time
Sucrose Breath test for sucrose malabsorption (sucrase-isomaltase deficiency)
Sorbitol Breath test for sorbitol malabsorption
Mannitol Breath test for mannitol malabsorption
How does the breath test work?
A wide range of sugars we ingest everyday, such as lactose and fructose, are usually absorbed within the small bowel. A large proportion of
people absorb these sugars poorly, allowing the sugars to pass into the colon, or large bowel. Fermentation of incompletely absorbed sugars
within the colon may result in the symptoms typical of irritable bowel syndrome (IBS), such as bloating, abdominal pain, excessive wind,
diarrhoea, constipation, or a mixture of both.
The breath test is based upon the fact that bacteria within the large bowel produce either hydrogen or methane gas (or a combination of
both) when ingested sugars are not completely absorbed by the small intestine.
The gas is absorbed into the bloodstream from the bowel and travels to the lungs where it is breathed out, allowing detection by hydrogen or
methane breath testing. Malabsorption of an orally ingested sugar such as lactose or fructose is indicated by a significant increase above
baseline levels in breath hydrogen or methane.
In patients suspected of having small bowel bacterial overgrowth, gas producing bacteria are also found in the small intestine. In this case
orally-ingested sugars such as glucose are fermented by bacteria in the small intestine before they can be absorbed leading to an increase in
breath hydrogen or methane.
The lactulose control test
Some patients are thought not to produce hydrogen in large amounts, so called “low-hydrogen producers,” and may instead produce other
gases such as methane. In addition, some patients may produce sufficient amounts of hydrogen, but it is quickly metabolised to produce
methane. Both of these situations may result in a patient with true sugar malabsorption having a “false-negative” hydrogen breath test, that
is, being told they don’t have sugar malabsorption when in fact they do. The rate of low-hydrogen producers quoted in the medical literature
ranges from 5-43%.
In order to maximise the accuracy and information obtained from a breath test, we believe it is important to have a baselinelactulose
hydrogen breath test. This test will enable our gastroenterologists to determine whether the bacteria within your bowel predominantly
produce either hydrogen or methane gas, thereby allowing us to perform subsequent tests measuring the most appropriate gas for you. In
addition to this, the lactulose control test allows us to accurately measure the oro-caecal transit time, that is the time taken for the sugar to
pass from your mouth to large bowel. As this time varies significantly between different people, knowing your personal transit time allows us
to tailor the duration of subsequent tests specifically for you.
As way of quality control, Gastrolab continues to monitor the latest research developments and as such procedures and protocols reflect
current best practice and are subject to change over time.
What happens during the test?
The hydrogen and methane breath test is simple, painless and non-invasive.
Please arrive for your appointment on time (preferably 10-15 minutes early) as late arrivals may be refused testing.
On the day of the breath test the technician will first check that you have observed the patient preparations, such as proper fasting and
avoiding certain medications and medical procedures prior to the test. This is to ensure accurate and reliable results.
A baseline reading will be taken using a highly sensitive, hand-held breathalyzer (for breath hydrogen), or using specialized breath collection
bags (for breath methane). Following the baseline reading you will be given a liquid sugar drink, such as lactulose, fructose, lactose or
glucose. Breath samples will then be collected regularly for a period of up to 3 hours, and the levels recorded by the laboratory technician on
your result sheet.
The test is performed in a group setting and you may wish to bring reading material, laptop, etc. to occupy your time. You may resume your
normal diet immediately after your test. You may experience certain gastrointestinal symptoms as a result of your test, such as bloating,
flatulence, or in less common cases, bowel motions. Side effects are not expected.
At the conclusion of the test your results will be interpreted by one of our gastroenterologists, and a summary of results and
recommendations will be sent to your referring clinician within two business days.
For dietary advice following a result suggesting malabsorption, Gastrolab can recommend an Accredited Practicing Dietician in your area
who specializes in gastrointestinal disorders and malabsorption.
Test Preparation
You must follow these instructions before each test to ensure accurate and reliable results. This will be verified on the day in order for your
test to proceed. Patients who do not follow these instructions may be refused testing or may have to reschedule.
1 week before your test:
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NO Oral and IV Antibiotics. Skin creams, eye and ear drops are OK.
NO Colonoscopy or Barium Meal Enema procedures.
1 full day before your test:
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RESTRICT Milk and Dairy Products. Lactose-free milk (eg. Zymil®), soy milk, and rice milk are OK.
RESTRICT Canned Fruit and Honey.
RESTRICT Fruit Juice, Soft Drinks, Sports Drinks and Alcohol.
RESTRICT High Fibre Foods (eg. beans & legumes, bran, oats)
NO Fibre Supplements (eg. Metamucil®).
NO Laxatives.
FAST from 9pm the night before test:
You may continue to drink plain water leading up to the test.
On the morning of your test:
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NO Smoking and Continue to Fast. Brush your teeth thoroughly with water ONLY (no toothpaste)
Continue to take your normal medication with plain water.
Refrain from physical exercise for 1 hour before your test.
You may wish to bring reading material, laptop, i-pod, etc. to occupy your time.