A CITRIC-ACID SOLUTION IS AN OPTIMAL TEST DRINK IN THE C-13-UREA BREATH TEST FOR THE DIAGNOSIS OF HELICOBACTER-PYLORI INFECTION

Background-The C-13-urea breath test (C-13-UBT) is a simple, non-invas ive and reliable test for the diagnosis of Helicobacter pylori infecti on. The duration of the test, the timing of breath sampling, and the a ccuracy of the method vary according to the test meal used. Aim-To ide ntify the optimal test meal or drink for rapid and accurate performanc e of the C-13-UBT for the detection of H pylori infection. Patients-Ei ghty patients with dyspeptic symptoms were included. Of these, 48 pati ents had a positive H pylori status and 32 a negative one according to the results of the rapid urease test, histological examination, and c ulture. Methods-A C-13-UBT was performed after an overnight fast, on t hree consecutive days. On each study day a different test meal or drin k was given (0.1 N citric acid solution, a standard semiliquid meal, o r a semiliquid fatty meal) 10 minutes before giving 75 mg C-13-urea. B reath samples were collected at 0, 15, 30, 45, and 60 minutes, and ana lysed by isotype ratio mass spectrometry. Results were expressed as de lta (delta) and considered as positive for H pylori if the highest del ta (peak) was greater than 4.0. Results-The delta peak obtained with t he citric acid drink in H pylori positive subjects (24.1 (SEM 1.5)) wa s significantly higher than that obtained with any of the semiliquid m eals (13.3 (SEM 1.1) and 17.1 (SEM 1.0) respectively, p < 0.001). Futh ermore, this 6 peak was obtained earlier with the citric acid drink (3 0 (SEM 2) minutes) than with the other two meals tested (53 (SEM 2) mi n and 45 (SEM 2) min, p < 0.001). The sensitivity of the C-13-UBT for the diagnosis of H pylori infection was 96-100% with all three test me als. This high sensitivity was, however, obtained from 15 minutes by g iving citric acid as the test drink, from 45 minutes by giving a semil iquid fatty meal, and at 60 minutes by giving the semiliquid standard meal. The specificity was 100% for all test meals. Citric acid is inex pensive and palatable to patients. Conclusions-The C-13-UBT procedure with citric acid as the test drink is superior to the previously propo sed semiliquid test meals in terms of (CO2)-C-13 recovery, time requir ement, and cost. In routine clinical sampling, collection at times 0 a nd 30 minutes seems to be optimal and gives a high diagnostic accuracy .