EFFECT OF A TEST MEAL ON THE INTRAGASTRIC DISTRIBUTION OF UREA IN THEC-13-UREA BREATH TEST FOR HELICOBACTER-PYLORI

Test meals are invariably used in the C-13, urea breath test (UBT) but their effect on the intragastric distribution and gastric residence t ime of urea given in the test is unknown. The site of Helicobacter pyl ori urease measured in the test is unknown and whether the test measur es total or regional gastric urease is uncertain. This study reports t he results of paired UBTs with simultaneous gastric distribution studi es, one with and one without a fatty test meal, two weeks apart on sev en H pylori infected subjects. The test meal did not affect UBT result s at 10 minutes, but increased values at 30 minutes and thereafter. Th e amount of scintigraphic label in the antrum at 10 minutes was also u naffected by the meal but increased at 30 minutes and thereafter, wher eas the amount in the body/fundus was greatly increased both at 10 min utes and throughout the test. There was considerable variation in intr agastric distribution of urea between subjects, both with and without the test meal. This study shows that a test meal profoundly affects in tragastric distribution of urea solution in the UBT, and increases UBT values at 30 minutes and later. Variability between subjects, however , means that accurate measurement of total or regional gastric urease is probably unrealistic.