[The H2-lactulose breath test in the diagnosis of intestinal transit time].

The H2-Lactulose breath test is used to detect small bowel bacterial overgrowth but mainly to evaluate the orocoecal transit time (OCTT) in man. The result of the H2-breath test is influenced by several intestinal and extraintestinal factors that cause a large variability of normal values. By reviewing the possible influencing factors of the breath tests we try to make a contribution to a better judgement of the results as the H2-lactulose breath-test is a simple noninvasive and non-expensive screening in the investigation of gastrointestinal disorders. For evaluating the better dosage of lactulose in gastroenterological routine diagnostic we designed a prospective study. The test was performed in 12 healthy volunteers by ingestion of 10 g and 20 g lactulose to quantitate the OCTT and to evaluate it in normal conditions. We found that the length of transit is related to the dose of lactulose. OCTT was 97.1 +/- 22.4 min. after ingestion of 10 g lactulose, and significantly shorter, 57.1 +/- 16.6 min. after ingestion of 20 g lactulose (p less than or equal to 0.01). The lower dose of lactulose is more suitable for routine diagnostic because of better acceptance despite slower transit time.