Hydrogen Breath Test
Encyclopedia
A hydrogen
breath test
(or HBT) is used as a clinical medical diagnosis
for people with irritable bowel syndrome
, and common food intolerance
s. The test is simple, non-invasive, and is performed after a short period of fasting
(typically 8–12 hours). Even though the test is normally known as a "Hydrogen Breath Test" some physicians may also test for methane
in addition to hydrogen. Many studies have shown that some patients (approximately 35% or more) do not produce hydrogen but actually produce methane. Some patients produce a combination of the two gases. Other patients don't produce any gas, which are known as "Non-Responders"; some physicians believe that these individuals actually produce another gas which has not been determined yet. In addition to hydrogen and methane, some facilities also utilize carbon dioxide
in the patients' breath to determine if the breath samples that are being analyzed are not contaminated (either with room air or bronchial dead space air).
Fructose malabsorption
- the patient takes a base reading of hydrogen levels in his/her breath. The patient is then given a small amount of fructose
, and then required to take readings every 15, 30 or 60 minutes for two to three hours. The basis of the test is a failure to absorb the given sugar, which is then metabolized by bacteria that give off either hydrogen or methane. Therefore, the more gas that is produced, the less absorption has occurred. If the level of hydrogen rises above 20 ppm (parts per million) over the lowest preceding value within the test period, the patient is typically diagnosed as a fructose malabsorber. If the patient produces methane then the parts per million for the methane typically rises 12 ppm over the lowest preceding value to be considered positive. If the patient produces both hydrogen and methane then the values are typically added together and the mean of the numbers is used to determine positive results, usually 15 ppm over the lowest preceding value.
Lactose malabsorption
- the patient takes a base reading of hydrogen levels in his/her breath. The patient is then given a small amount of pure lactose
(typically 20 to 25 g), and then required to take readings every 15, 30 or 60 minutes for two to three hours. If the level of hydrogen rises above 20 ppm (parts per million) over the lowest preceding value within the test period, the patient is typically diagnosed as a lactose malabsorber
. If the patient produces methane then the parts per million for the methane typically rises 12 ppm over the lowest preceding value to be considered positive. If the patient produces both hydrogen and methane then the values are typically added together and the mean of the numbers is used to determine positive results, usually 15 ppm over the lowest preceding value. However, recent study suggest that testing may not correlate with any actual diagnosis.
Small Bowel Bacterial Overgrowth Syndrome
(SBBOS) or Small Intestinal Bacterial Overgrowth (SIBO) - the patient is either given a challenge dose of glucose, also known as dextrose (75-100 grams), or lactulose (10 grams). A baseline breath sample is collected, and then additional samples are collected at 15 minute or 20 minute intervals for 3–5 hours. Positive diagnosis for a lactulose SIBO breath test - typically positive if the patient produces approximately 20 ppm of hydrogen and/or methane within the first two hours (indicates bacteria in the small intestine), followed by a much larger peak (colonic response). This is also known as a biphasic pattern. Lactulose is not absorbed by the digestive system and can help determine distal end bacterial overgrowth, which means the bacteria are lower in the small intestine.
Positive diagnosis for a glucose SIBO breath test - glucose is absorbed by the digestive system so studies have shown it to be harder to diagnose distal end bacterial overgrowth since the glucose typically doesn't reach the colon before being absorbed. An increase of approximately 12 ppm or more in hydrogen and/or methane during the breath test could conclude bacterial overgrowth. Recent study indicates "The role of testing for SIBO in individuals with suspected IBS remains unclear."
The excess hydrogen or methane is assumed to be typically caused by an overgrowth of otherwise normal intestinal bacteria
.
Other breath tests that can be taken include: Sucrose Intolerance, d-xylose
and sorbitol
.
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...
breath test
Breath test
A breath test is a type of test performed on air generated from the act of exhalation.Types include:*Breathalyzer - By far the most common usage of this term relates to the legal breath test to determine if a person is driving under the influence of alcohol.*Hydrogen breath test - it is becoming...
(or HBT) is used as a clinical medical diagnosis
Diagnosis
Diagnosis is the identification of the nature and cause of anything. Diagnosis is used in many different disciplines with variations in the use of logics, analytics, and experience to determine the cause and effect relationships...
for people with irritable bowel syndrome
Irritable bowel syndrome
Irritable bowel syndrome is a diagnosis of exclusion. It is a functional bowel disorder characterized by chronic abdominal pain, discomfort, bloating, and alteration of bowel habits in the absence of any detectable organic cause. In some cases, the symptoms are relieved by bowel movements...
, and common food intolerance
Food intolerance
Food intolerance or non-allergic food hypersensitivity is a term used widely for varied physiological responses associated with a particular food, or compound found in a range of foods....
s. The test is simple, non-invasive, and is performed after a short period of fasting
Fasting
Fasting is primarily the act of willingly abstaining from some or all food, drink, or both, for a period of time. An absolute fast is normally defined as abstinence from all food and liquid for a defined period, usually a single day , or several days. Other fasts may be only partially restrictive,...
(typically 8–12 hours). Even though the test is normally known as a "Hydrogen Breath Test" some physicians may also test for methane
Methane
Methane is a chemical compound with the chemical formula . It is the simplest alkane, the principal component of natural gas, and probably the most abundant organic compound on earth. The relative abundance of methane makes it an attractive fuel...
in addition to hydrogen. Many studies have shown that some patients (approximately 35% or more) do not produce hydrogen but actually produce methane. Some patients produce a combination of the two gases. Other patients don't produce any gas, which are known as "Non-Responders"; some physicians believe that these individuals actually produce another gas which has not been determined yet. In addition to hydrogen and methane, some facilities also utilize carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
in the patients' breath to determine if the breath samples that are being analyzed are not contaminated (either with room air or bronchial dead space air).
Conditions
Tests vary from country to country, so the following information is provided as a rough guide to typical uses of the hydrogen breath test:Fructose malabsorption
Fructose malabsorption
Fructose malabsorption, formerly named "dietary fructose intolerance," is a digestive disorder in which absorption of fructose is impaired by deficient fructose carriers in the small intestine's enterocytes. This results in an increased concentration of fructose in the entire intestine.Fructose...
- the patient takes a base reading of hydrogen levels in his/her breath. The patient is then given a small amount of fructose
Fructose
Fructose, or fruit sugar, is a simple monosaccharide found in many plants. It is one of the three dietary monosaccharides, along with glucose and galactose, that are absorbed directly into the bloodstream during digestion. Fructose was discovered by French chemist Augustin-Pierre Dubrunfaut in 1847...
, and then required to take readings every 15, 30 or 60 minutes for two to three hours. The basis of the test is a failure to absorb the given sugar, which is then metabolized by bacteria that give off either hydrogen or methane. Therefore, the more gas that is produced, the less absorption has occurred. If the level of hydrogen rises above 20 ppm (parts per million) over the lowest preceding value within the test period, the patient is typically diagnosed as a fructose malabsorber. If the patient produces methane then the parts per million for the methane typically rises 12 ppm over the lowest preceding value to be considered positive. If the patient produces both hydrogen and methane then the values are typically added together and the mean of the numbers is used to determine positive results, usually 15 ppm over the lowest preceding value.
Lactose malabsorption
Lactose intolerance
Lactose intolerance, also called lactase deficiency or hypolactasia, is the inability to digest and metabolize lactose, a sugar found in milk...
- the patient takes a base reading of hydrogen levels in his/her breath. The patient is then given a small amount of pure lactose
Lactose
Lactose is a disaccharide sugar that is found most notably in milk and is formed from galactose and glucose. Lactose makes up around 2~8% of milk , although the amount varies among species and individuals. It is extracted from sweet or sour whey. The name comes from or , the Latin word for milk,...
(typically 20 to 25 g), and then required to take readings every 15, 30 or 60 minutes for two to three hours. If the level of hydrogen rises above 20 ppm (parts per million) over the lowest preceding value within the test period, the patient is typically diagnosed as a lactose malabsorber
Lactose intolerance
Lactose intolerance, also called lactase deficiency or hypolactasia, is the inability to digest and metabolize lactose, a sugar found in milk...
. If the patient produces methane then the parts per million for the methane typically rises 12 ppm over the lowest preceding value to be considered positive. If the patient produces both hydrogen and methane then the values are typically added together and the mean of the numbers is used to determine positive results, usually 15 ppm over the lowest preceding value. However, recent study suggest that testing may not correlate with any actual diagnosis.
Small Bowel Bacterial Overgrowth Syndrome
Small bowel bacterial overgrowth syndrome
Small bowel bacterial overgrowth syndrome , or small intestinal bacterial overgrowth , also termed bacterial overgrowth; is a disorder of excessive bacterial growth in the small intestine. Unlike the colon , which is rich with bacteria, the small bowel usually has less than 104 organisms per...
(SBBOS) or Small Intestinal Bacterial Overgrowth (SIBO) - the patient is either given a challenge dose of glucose, also known as dextrose (75-100 grams), or lactulose (10 grams). A baseline breath sample is collected, and then additional samples are collected at 15 minute or 20 minute intervals for 3–5 hours. Positive diagnosis for a lactulose SIBO breath test - typically positive if the patient produces approximately 20 ppm of hydrogen and/or methane within the first two hours (indicates bacteria in the small intestine), followed by a much larger peak (colonic response). This is also known as a biphasic pattern. Lactulose is not absorbed by the digestive system and can help determine distal end bacterial overgrowth, which means the bacteria are lower in the small intestine.
Positive diagnosis for a glucose SIBO breath test - glucose is absorbed by the digestive system so studies have shown it to be harder to diagnose distal end bacterial overgrowth since the glucose typically doesn't reach the colon before being absorbed. An increase of approximately 12 ppm or more in hydrogen and/or methane during the breath test could conclude bacterial overgrowth. Recent study indicates "The role of testing for SIBO in individuals with suspected IBS remains unclear."
The excess hydrogen or methane is assumed to be typically caused by an overgrowth of otherwise normal intestinal bacteria
Gut flora
Gut flora consists of microorganisms that live in the digestive tracts of animals and is the largest reservoir of human flora. In this context, gut is synonymous with intestinal, and flora with microbiota and microflora....
.
Other breath tests that can be taken include: Sucrose Intolerance, d-xylose
Xylose
Xylose is a sugar first isolated from wood, and named for it. Xylose is classified as a monosaccharide of the aldopentose type, which means that it contains five carbon atoms and includes an aldehyde functional group. It is the precursor to hemicellulose, one of the main constituents of biomass...
and sorbitol
Sorbitol
Sorbitol, also known as glucitol, Sorbogem® and Sorbo®, is a sugar alcohol that the human body metabolizes slowly. It can be obtained by reduction of glucose, changing the aldehyde group to a hydroxyl group. Sorbitol is found in apples, pears, peaches, and prunes...
.
External links
- Hydrogen Breath Test References contains patient and physician information, articles and abstracts.
- Breath Tests and Gastroenterology from Dr. Lyle Hamilton, Ph.D - contains information on the principle of breath test as well as extensive references to breath testing.
- Hydrogen Breath Test information from MedicineNet.
- Hydrogen Breath Test information from the University of Michigan Health System
- Hydrogen Breath Test information from the GP Notebook
- Patient and Physician Information Testing information for physicians and patients..