It’s a non-invasive procedure, which serves to detect in the exhaled air H2 (hydrogen gas) produced in the course of poorly digested carbohydrates. It provides information on a range of conditions depending on what kind of liquid we give the patient:
Inability to process lactose: Lactose, found in milk, is a so/called disaccharide, comprising glucose and galactose. The body needs the enzyme lactase to break it down. Disaccharides can only be absorbed in the small intestine once broken down. In the absence of the enzyme lactase, the sugar in milk (lactose) does not break down, so gets into the large intestine, where it is processed by bacteria. During this process, H2 is produced, which is absorbed into the blood, and thus is pumped into the lungs, which is where it gets detected by the instrument.
The lactulose test where H2 is examined in the exhaled air is suitable for determining the time it takes food to pass through the small intestine (small intestine transit time) as well as detecting if there exists a pathologically excessive bacterial presence in the small intestine (contaminated small intestine syndrome).
Lactulose is a disaccharide, a sugar derivative only digestible by intestinal bacteria, the enzymes of the small intestine can’t process it, so it passes on into the large intestine practically unchanged. It gets to work in the large intestine, where, in response to intestinal bacteria, it transforms into short-chain carbonic acids, primarily lactose and acetyl, as well as methane and hydrogen gases.
Analysis of the examination results: the time food takes to pass through the small intestine (transit time) is indicated by the point when change in concentration exceeds the threshold of 20 ppm. Normal transit times can be determined by an examination of a normal control group. This time is 120 minutes on average. If the H2 exhalation test, done with glucose, shows disease, i.e. shows a shorter-than-control time, this is indicative of bacterial contamination of the small intestine, while if it is normal, we measure transit time.
Starch load refers to the functioning of the pancreas. The enzyme amylase breaks down starch, H2 produced in the process is measureable.