[Methodological study of 13C-urea breath test for detection of Helicobacter pylori infection]

In this study, we investigate simple breath test for detection of Helicobacter pylori (HP) infection using 13C-urea. Thirty-nine patients (30 were HP positive, 9 were HP negative) were given three different doses (50, 100 and 150 mg) of 13C-urea at fasting, and keep sitting after mouth washing with water. Breath samples were taken before and 10, 20, 30, 45, and 60 minutes after urea administration. More than 100mg of 13C-urea was necessary for correct diagnosis of HP infection, because 2 HP positive cases were not detected by 50mg 13C-urea administration. In cases with patchy distribution of HP in the stomach, it may be necessary to change the posture to distribute urea within the whole stomach. In most of HP positive cases, peak delta 13CO2 were obtained within 30 minutes, but one HP negative case showed high delta 13CO2 at 10 minutes, which was probably caused by urease activity in the mouth. So it is appropriate to take breath sample at 20 minutes after urea administration. In this study, cut-off value for a positive test can be setted between 4 to 7 delta/1000, it is necessary to investigate much more cases to set exact cut-off value.