Efficacy of lactulose plus 13C-acetate breath test in the diagnosis of gastrointestinal motility disorders

Background. We designed a new method of measuring gastric emptying and orocecal transit time (OCTT) at the same time to assess the influence of gastric emptying upon OCTT. Methods. Twenty-five dyspeptic patients (6 men, 19 women) with a mean age of 64.8 years (range, 25-80 years) were studied. The patients received a liquid test meal, containing 100 mg Of C-13-acetate and 12 g of lactulose, while they were in the sitting position after an overnight fast. Breath samples were collected at 10-min intervals of 120 min and both (CO2)-C-13 and hydrogen (H-2) levels were measured. Subsequently, H-2 concentrations were measured at 30-min intervals, for a total of 240 min. Results. The results of gastric emptying were expressed as the time of peak (CO2)-C-13 excretion. OCTT was defined as the period between the ingestion of lactulose and a H-2 peak rise of 5 ppm above the baseline value. The onset of H-2 enrichment in the breath began at 90-110 min. whereas (CO2)-C-13 levels increased from the beginning. with peak enrichment values being reached after 60-80 min. OCTT was related to (CO2)-C-13 peak time. In 5 of the 25 patients, H-2 breath enrichment in the 10-min sample was more than 5 ppm over the baseline value. All these 5 patients had double or triple peaks in serial breath H. concentrations. Conclusions. The combination of the lactulose hydrogen breath test (LHBT) with the C-13-acetate breath test. which requires only breath samples, provides us with much information on the gastrointestinal tract; gastric emptying. OCTT. bacterial overgrowth in the small intestine, colonic fermentation, and oropharyngeal flora. The C-13-acetate breath test can be useful as an adjuvant test when LHBT is performed for measuring OCTT.