UREA BREATH TESTS IN THE MANAGEMENT OF HELICOBACTER-PYLORI INFECTION

The C-13/14-Urea breath test (UBT) is based on the simple principle th at a solution of isotopically labelled urea will be rapidly hydrolysed by the abundantly expressed urease of H pylori. The released (CO2)-C- 13/14 is absorbed across the mucus layer to the gastric mucosa and hen ce, via the systemic circulation, excreted in the expired breath. Dist ribution of urea throughout the stomach prevents sampling error and al lows semiquantitative assessments of the extent of H pylori infection. Originally the C-13-UBT was complex, cumbersome and costly but, by si mplifying the protocol and reducing the number of samples to be analys ed, is now a much easier, quicker and cheaper test for detecting H pyl ori. Although mass spectrometry is needed for analysis of exhaled (CO2 )-C-13, the use of the stable isotope, which is completely safe, provi des advantages over the C-14-UBT using radioactive C-14-urea, such tha t it can be used in women and children and a user's licence is not req uired. The widespread availability of scintigraphy for (CO2)-C-14 anal ysis may make the C-14-UBT seem an attractive alternative to the C-13- UBT. However, there are no standard protocols for the C-14-UBT and alt hough the methods are similar, several different cut off values are us ed which makes formal validation studies still necessary. Both tests a re easy to perform with minimum opportunity for observer variation or methodological error; they are very sensitive and specific tests and p rovide a clinical ''gold standard'' against which the accuracy of othe r tests can be validated. The C-13/14-UBT detects only current infecti on and can be used to screen for H pylori infection and as the sole me thod for assessing eradication. In addition, because the C-13-UBT can be performed repeatedly in the same subject, it can be used to monitor the effects of novel anti-H pylori therapies and for epidemiological studies in children.