Value of lactulose hydrogen breath test combined with radionuclide imaging in the diagnosis of small intestinal bacterial overgrowth

Abstract

Objective To compare the tracing effects of radionuclide and barium sulfate on lactulose hydrogen breath test (LHBT), and to explore the value of LHBT combined with radionuclide imaging in the diagnosis of small intestinal bacterial overgrowth (SIBO) in patients with irritable bowel syndrome (IBS). Methods From November 2010 to November 2012, 89 patients (47 males, 42 females; mean age (45.7±12.9) years) with IBS and 13 healthy volunteers (9 males, 4 females; mean age (43.3±8.6) years) were enrolled in this prospective study. All the subjects underwent LHBT combined with radionuclide imaging. Recording the time when the increment of H2 value >0.005‰ and the OCTT of the radionuclide. Four healthy volunteers also underwent LHBT combined with barium sulfate 1 week after radionuclide imaging. The location of barium sulfate was recorded when H2 value increment >0.020‰. Patients with SIBO received rifaximin treatment, and the effect was observed. χ2 test, Pearson correlation analysis and Wilcoxon rank sum test were used to analyze the data. Results (1)In LHBT combined with barium sulfate test, barium sulfate was found still stagnating in small intestine by abdominal X-ray when H2 value increment >0.020‰ in 4 healthy volunteers, and barium sulfate didn′t reach the colon in delayed imaging in 1 patient. (2) The rates of SIBO detected by LHBT in IBS patients and healthy volunteers were significantly different (43.8%(39/89) vs 5/13; χ2=0.133, P=0.716), and those detected by LHBT combined with radionuclide imaging were also significantly different (39.3%(35/89) vs 1/13; χ2=4.970, P=0.026). (3)The time of H2 value increased >0.005‰ correlated well with OCTT in 13 healthy volunteers ((73±31) and (50±19) min; r=0.871, P<0.001) and 54 IBS patients without SIBO ((83±34) and (66±28) min; r=0.735, P<0.001), but there was no correlation in 35 IBS patients with SIBO ((36±30) and (75±30) min ; r=0.304, P=0.076). (4)A total of 34 SIBO-positive patients received a rifaximin treatment, with a significant improvement in the frequency of abdominal pain and abdominal distension after the treatment according to Rome Ⅲ diagnostic criteria: 5(4, 6) vs 4(3, 5), 4(1, 6) vs 0(0, 4)(z values: -4.842 and -5.388, both P<0.001). Conclusion LHBT alone is not a valid test for SIBO, and LHBT combined with radionuclide imaging is a good candidate for SIBO diagnosis. Key words: Blind loop syndrome; Irritable bowel syndrome; Breath tests; Lactulose; Hydrogen; Technetium Tc 99m pentetate