[Lactulose hydrogen breath test in small intestinal bacterial overgrowth]

Lactulose hydrogen breath test (LHBT) was evaluated in 21 patients suspected of having small intestinal bacterial overgrowth syndrome and 10 healthy volunteers as control. After dietary preparation and a 12-hour fast, subjects received 15g of lactulose mixed with 40% barium sulfate. The purpose of the barium meal was to reveal the position of lactulose in the intestines. End-expiratory samples of breath were taken at 15 minutes intervals at least for 4 hours. Breath hydrogen was measured with gas chromatography. A positive LHBT was defined as increase of hydrogen concentration in the breath more than 10 x 10(-6) above the baseline value before barium reached the sixth group of small intestine. Cultures were considered positive for bacterial overgrowth when anaerobic counts > or = 10(6) CFU/ml of aspirate. The procedure was carried out under sterile condition. Compared with the bacteriologic culture, LHBT has a sensitivity of 71.4%, specificity of 88.2% and accuracy of 80.6%. These results show that the LHBT is a simple, non-invasive and relatively reliable method for diagnosis of small intestinal bacterial overgrowth.