[Intestinal function tests]

Diagnostic techniques investigating intestinal functions are a main component of gastroenterological diagnostic procedures and are mainly indicated if intestinal motility disturbances or malabsorption syndromes are suspected. H2 breath tests using lactulose or lactitol as substrates measure orocecal transit time. Intestinal manometry allows more detailed analysis of intestinal motility disturbances but is only available at specialized centres. A generalized malabsorption syndrome can be diagnosed by D-xylose test. If it is caused by bacterial overgrowth, the H2 breath test with glucose may be helpful. Lactose intolerance is the most frequently observed intestinal malfunction and affects about 70% of people worldwide. At present, the lactose H2 breath test is the diagnostic procedure of choice to prove lactose malabsorption. Clinically relevant insufficiencies of other intestinal disaccharidases are rare, but may indicate H2 breath tests with specific substrates. Recently developed 13C breath tests using stable, non-radioactive substrates may extend our diagnostic options considerably and may allow more detailed information about intestinal (mal-)functions as a prerequisite for optimized therapy.