Negative effect of ranitidine on the results of urea breath test for the diagnosis of Helicobacter pylori

OBJECTIVES: In analogy with proton pump inhibitors, H2-antagonists may also be responsible for false-negative results on urea breath test for the dete ction of Helicobacter pylori. In this study we assessed the frequency and d uration of false-negative urea breath tests in patients given different dos es of ranitidine. METHODS: A total of 120 consecutive dyspeptic patients: infected with H. py lori on the basis of concomitant positive results of CLO-test, histology an d urea breath test were: recruited for this prospective, open, parallel-gro up study performed in an urban university gastroenterological clinic. They were: randomized to receive an acute treatment with either ranitidine 300 m g once a day in the evening, ranitidine 300 mg once a day in the morning, r anitidine 150 mg b.i.d., or ranitidine 300 mg b.i.d. for 14 days. The urea breath test was performed on day 14 while patients were still taking raniti dine, and on day 21, 1 wk after completion of therapy. The test was repeate d on day 28 in those patients who were still negative on day 21. Duplicate breath samples were collected after ingestion of 75 mg C-13-urea plus citri c acid. A delta value >5 parts per thousand was considered positive. RESULTS: Of 118 patients infected with H. pylori, 15 (13%) had a negative u rea breath test on day 14. The false-negative results were equally distribu ted among the four groups of ranitidine dosage. Nine of these patients: rev erted to positive at 7 days and the remaining six at 14 days after completi on of therapy. CONCLUSIONS: Our study shows that ranitidine negatively affects the results of urea breath testing, independent of the given dosage. Patients undergoi ng this examination for H. pylori diagnosis should discontinue use of H2-an tagonists 2 wk before testing.