BREATH TEST - HYDROGEN FOR THE DETECTION OF LACTOSE INTOLERANCE

New Test in CIC Catalog

Test Code: 3999

Sample:	Special tube provided by CIC
Conservation:	Room temperature
Method:	Gas Chromatography/Mass Spectrometry (LOINC®: GC/MS)
Set Up Days:	Daily
TAT (Days):	4 days
Information:
Approximately half of our daily need of calories derived from carbohydrates. Most of these are ingested in the form of starch, which by salivary and pancreatic amylase is hydrolyzed and gives rise to oligosaccharides and then disaccharides (sucrose, maltose and lactose) and monosaccharides (glucose fructose and galactose). The latter are absorbed directly into the small intestinal epithelium without previous digestion. However, the disaccharides must be cleaved by enzymes previously found in the villous epithelial cells. An insufficient digestion or absorption of carbohydrates exposed them to a bacterial fermentation in the distal small intestine and colon. During fermentation originate short chain fatty acids and gases such as carbon dioxide (C02) and hydrogen (H2). These gases diffuse partially into the blood and are then exhaled. Because the body H2 is formed exclusively by bacterial fermentation of carbohydrates, the concentration of H2 in the exhaled air reflects the decomposition thereof in the intestine. Therefore, the determination of H2 can be used in the exhaled air to show an abnormal breakdown and poor absorption of carbohydrates. Fasting produces little or no H2 excretion through the lungs. However, the appearance of H2 with fasting can be relatively high if the intestine due to an insufficient fasting, it contains many carbohydrate residues. If a carbohydrate, after being administered is not completely absorbed increases the excretion of H2. However, if the absorption is insufficient, one part arrives at the colon and fermentation occurs with the consequent production of H2. In the case of bacterial overgrowth in the small intestine, the fermentation of carbohydrates can increase the excretion of H2 at 30-45 min after administration. This increase reflects the fermentation of the unabsorbed part of the carbohydrate. Thus, when using differents types of carbohydrates can be demonstrated alterations in the digestion and absorption of monosaccharides, disaccharides or polysaccharides. In an insufficient absorption of any carbohydrate is followed by production of H2, and consequently a positive breath hydrogen tests. In some individuals the bacteria colonizing the colon are not producing H2 and instead produce methane (CH4), so it is recommended that the joint determination of these two gases.

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