Hydrogen Breath Test
A hydrogen breath test provides
information about the digestion of certain sugars or carbohydrates, such as milk
sugar (lactose) or fruit sugar (fructose). This will help determine if you are
intolerant to certain sugars. One example is the use of this test to detect
lactose intolerance, a disorder in which people have symptoms from abnormal
processing of lactose, a substance in many foods including milk and ice cream.
The test is also used for detecting abnormal growth of bacteria within the small
bowel by having the patient ingest lactulose. Bacterial overgrowth can cause a
variety of symptoms including diarrhea, bloating, gas and abdominal cramps.
Principles of Hydrogen Breath Testing
Hydrogen gas in the body is produced from intestinal bacteria. Bacteria,
normally in the large intestine, produce hydrogen through fermentation of
carbohydrates – such as lactose, lactulose and fructose which are substrates
given for the hydrogen breath test. Some of the hydrogen produced by bacteria is
absorbed by intestinal mucosa whereby it enters the vasculature and is
transported to the lungs. Hydrogen is then exhaled by the lungs by normal
breathing. This is collected in the bag for subsequent analysis.
In small intestinal bacterial overgrowth, the small intestinal bacteria
metabolize the lactulose given and produce an early rise in the breath hydrogen.
In lactose intolerance, the individual has a deficiency in lactase, the enzyme
that breaks down lactose. Normally, lactose is broken down in the small
intestine by lactase and very little lactose reaches the large intestine where
the bacteria break it down to produce hydrogen. In lactose intolerance (lactase
deficiency), the ingested lactose is not metabolized in the small intestine and
reaches the colon where it is metabolized by colonic bacteria producing a large
amount of hydrogen which is measured in the breath sample.
Patient Instructions for Hydrogen Breath Test for
Bacterial Overgrowth
Patient Instructions for Hydrogen Breath Test for Lactose
Intolerance |
