¹³C-urea breath test in the management of Helicobacter pylori infection

Abstract

The urea breath test is a noninvasive and very accurate test for the diagnosis of Helicobacter pylori infection. However, false negative urea breath test results have been reported to occur in a considerable percentage of the individuals taking proton pump inhibitors; the interval needed to be completely confident that false negative tests had been excluded has varied among the different studies between 6 and 14 days. The impact of H₂-receptor antagonists on the accuracy of urea breath test remains controversial, although, in contrast with proton pump inhibitors, the data suggest that H₂-receptor antagonists, for the most part, have little effect on the result of the urea breath test. The urea breath test does not represent a suitable tool for estimating the density of H. pylori colonization. The only quantitative information to be obtained from the urea breath test is that the higher the δ value, the lower the probability of a false-positive urea breath test result. Although some authors have demonstrated a correlation between urea breath test values and histological lesions of the gastric mucosa, the practical utility of this relationship remains unclear. It has been suggested that the pretreatment urea breath test has the potential to identify patients who require modification of the standard therapeutic regimen (for example, prolonging the duration of treatment or increasing the pharmacological dose when bacterial density is high), but other studies could not confirm this relationship. Some studies have shown that the urea breath test is less accurate in patients who have undergone partial gastrectomy. Finally, in contrast with biopsy-based methods, which are responsible for a high number of false-negative results when used to diagnose H. pylori infection in patients with upper gastrointestinal bleeding, urea breath test seems not to be negatively influenced by the presence of this complication.

Introduction

Diagnostic methods for H. pylori infection have been traditionally divided into invasive and noninvasive. Indirect or noninvasive techniques do not necessitate an endoscopy and are therefore, more convenient and cheaper for the patient, and thus should be preferred in situations where the extra information yielded by an endoscopy is not needed. Urea breath test (UBT) has proved to be one of the most accurate methods for assessing H. pylori status, as it is simple, innocuous, easy to repeat and highly accurate [1]. Since the original description by Graham et al. of the ¹³C-UBT to specifically diagnose H. pylori infection [2], numerous modifications have been proposed for the UBT technique, and a multitude of papers regarding its methodology have been published, in spite of which a definitive standardisation of this test does not yet exist. In a previous study [3], we reviewed several aspects of the UBT protocol, such as the measuring equipment, necessity of fasting before testing, type of test meal, dose of urea, necessity of basal breath samples, breath sampling time after urea ingestion and the cut-off point for discriminating between positive and negative tests. The aim of the present article will be to review additional aspects of the UBT, such as (1) false-negative results in patients taking proton pump inhibitors (PPIs) and H₂-blockers; (2) UBT as an estimate of the extent of the H. pylori infection and the gastric histological lesions; (3) UBT as a predictor of response to H. pylori eradication treatment; (4) the accuracy of UBT in partial gastrectomy patients; and (5) the accuracy of UBT in upper gastrointestinal bleeding. This review will be focused on ¹³C-UBT (that is, the nonradioactive stable isotope), as it is completely innocuous and has become the most widely used.