BackgroundThe13C-urea breath test is an accurate, noninvasive method for the diagnosis ofHelicobacter pyloriin adults. A dose of 75 to 100 mg of urea is generally used, especially in adults, but the optimal dose in children is still unknown. Our aim was to determine whether urea breath test performed with a single 50-mg dose of13C-urea was sufficient and accurate for diagnosingH. pyloriinfection in children.MethodsConsecutive children 4 to 14 years of age undergoing upper intestinal endoscopy to evaluate symptoms of recurrent abdominal pain were prospectively included. Exclusion criteria included use of antibiotics or proton pump inhibitors during the last month, gastric surgery, and previousH. pylorieradication therapy. Reference criteria for diagnosis of infection were based on histology, culture, and serology. Urea breath test (TAU-KIT; Isomed, S.L., Madrid, Spain) was performed as follows: citric acid (Citral pylori) dissolved in 100 mL of water was initially given. Ten minutes later, a baseline exhaled breath sample was collected, and thereafter 50 mg of13C-urea dissolved in 50 mL of water was given. A second breath sample was obtained 30 minutes later. Breath samples were analyzed by isotope ratio mass spectrometry. The endoscopist, the pathologist, the microbiologist, and the person responsible for reading the serology and the urea breath test were all unaware ofH. pyloristatus by the other diagnostic methods.ResultsOne hundred children were included (40% males; mean age, 9.2 ± 2 years; mean weight, 33.9 ± 12 kg). Based on the reference criteria, 45% were infected, 37% were not infected, and 18% were indeterminate. Sensitivity, specificity, positive predictive value, and negative predictive value were, respectively, 91% (95% confidence interval [CI], 79%–96%), 97% (95% CI, 86%–99%), 98% (95% CI, 87%–91%), and 90% (95% CI, 76%–96%). Positive and negative likelihood ratios were of 33 and 0.09. Any cutoff point between 2 and 14 &dgr; units had the same high diagnostic accuracy. The area under the receiver operating characteristic curve was 0.94. No adverse effects were reported.ConclusionUrea breath test using 50 mg of urea is sufficient and accurate for the diagnosis ofH. pyloriinfection in children. Use of a small test dose significantly lowers the cost of the test.