Hydrogen breath test or HBT is very useful for diagnosing patients suffering from carbohydrate intolerance, such as lactose and fructose malabsorption, and small intestinal bacterial overgrowth (SIBO). As such HBT is challenging the quantitative culture of jejuna aspirate methodology, typically employed for diagnosing SIBO. This is primarily because of the non-invasive nature of HBT. Also, HBT is far simpler than that of quantitative culture of jejuna aspirate methodology used as the gold standard for diagnosing SIBO.
There are two types of HBT, glucose hydrogen breath test and Lactulose Hydrogen Breath Test. The uses of HBT are stated in the following section.
There are three main purposes for which a glucose or lactulose hydrogen breath test can be used. These are:
For checking a patient for Fructose Malabsorption, first of all a base reading of hydrogen levels in the breath is collected. Then a small amount of fructose is given to the patient. Subsequent readings are taken every 15, 30 or 60 minutes gap for about 2 to 3 hours. The test is based on the fact that when the given sugar, fructose, is failed to be absorbed by the patient, then the bacteria metabolize and gives off either methane or hydrogen indicative of the patient’s inability to absorb fructose.
Lactulose hydrogen breath test is used for checking a patient for Lactose Malabsorption. Before starting the test, a base reading of hydrogen levels in the patient breath is collected. Thereafter, the patient is given about 20-25 grams pure lactose. Recordings are then collected every 15, 30 or 60 minutes interval for about 2 to 3 hours. The final results could suggest one of the three things:
The patient is a lactose malabasorber if the hydrogen levels of the lactulose hydrogen breath test comes out to be more than 20 ppm (parts per million)
The patient is not a lactose malabsorber but prone to Lactose Malabsorption if the patient produces methane levels above 12 ppm
The patient is healthy if the patient produces both good levels of hydrogen and methane with a mean value of over 15 ppm.
Small Intestinal Bacterial Overgrowth (SIBO)
Also known as small bowel bacterial overgrowth syndrome (SBBOS), the patient suffering from SIBO is either given a challenge dose of dextrose (a type of glucose) or lactulose, 75 to 100 grams and 10 grams respectively. The first baseline breath sample is collected immediately, while subsequent samples are collected for 3 to 5 hours with regular intervals of 15 to 20 minutes.
Patients that produce about 20 ppm of hydrogen and/or methane in the first 2 hours, followed by a much larger peak afterwards is considered a positive diagnosis for a lactulose hydrogen breath test. The response is also known as a biphasic pattern. As lactulose is not absorbed by the digestive system, it can determine the distal end bacterial overgrowth. Further treatment is based on the results of the lactulose hydrogen breath test.