CARBOHYDRATE MALABSORPTION - QUANTIFICATION BY METHANE AND HYDROGEN BREATH TESTS

Background: Previous studies in small series of healthy adults have su ggested that parallel measurement of hydrogen and methane resulting fr om gut fermentation may improve the precision of quantitative estimate s of carbohydrate malabsorption. Systematic, controlled studies of the role of simultaneous hydrogen and methane measurements using end-expi ratory breath test techniques are not available. Methods: We studied s even healthy, adult methane and hydrogen producers and seven methane n on-producers by means of end-expiratory breath test techniques. Breath gas concentrations and gastrointestinal symptoms were recorded at int ervals for 12 h after ingestion of 10, 20, and 30 g lactulose. Results : In the seven methane producers the excretion pattern was highly vari able; the integrated methane responses were disproportional and not re liably reproducible. However, quantitative estimates of carbohydrate m alabsorption on the basis of individual areas under the methane and hy drogen excretion curves (AUCs) tended to improve in methane producers after ingestion of 20 g lactulose by simple addition of AUCs of methan e to the AUCs of the hydrogen curves. Estimates were no more precise i n methane producers than similar estimates in non-producers. Gastroint estinal symptoms increased significantly with increasing lactulose dos e; correlation with total hydrogen and methane excretion was weak. Con clusions: Our study suggests that in methane producers, simple additio n of methane and hydrogen excretion improves the precision of semiquan titative measurements of carbohydrate malabsorption. The status of met hane production should, therefore, be known to interpret breath tests semiquantitatively. The weak correlation between hydrogen and methane excretion and gas-related abdominal complaints suggests that other fac tors than net production of these gases may be responsible for the sym ptoms.