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Refinement of the 14C-urea Breath Test for Detection of Helicobacter pylori

Background: Helicobacter pylori is recognized as the main etiological factor for chronic gastritis, peptic ulcer and possibly also gastric malignancies. A 14C-urea breath test was successively refined to correctly diagnose the presence of H. pylori. Methods: After intake of a 14C-urea cocktail, 14CO2 in breath was trapped in benzethoniumhydroxide/ethanol. Serology by ELISA, followed by Western blot, was used as reference method for confirmation of presence or absence of H. pylori. Results: Breath measurements at 10 and 20 min were determined to be optimal for diagnostic purposes. With 2.5 µCi of 14C-urea, a sensitivity of 86% and specificity of 100% was obtained for the 10-min values. Corresponding data for the 20-min values were 86% and 99%, respectively. When 50 mmol L-1 citric acid was added to the 2.5 µCi 14C-urea cocktail, separation between positive and negative results became more distinct along with improved sensitivity of 91% and specificity of 100%. As the isotope amount was reduced to 1.0 µCi in the citric acid-containing cocktail, a sensitivity of 93% and specificity of 100% were obtained at both 10 and 20 min. Conclusion: Diagnostic urea breath test has a high concordance with H. pylori serology, combining ELISA and Western blot. Stepwise refinements proved the optimal urea breath test cocktail to include 1.0 µCi 14C-urea in citric acid solution with breath measurement at 10 min.