title: Breath test using a single 50-mg dose of 13C-urea to detect Helicobacter pylori infection in children.
abstract: BACKGROUND
  The 13C-urea breath test is an accurate, noninvasive method for the diagnosis of in 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 of 13C-urea was sufficient and accurate for diagnosing infection in children.
  
  
  METHODS
  Consecutive 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 previous eradication 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 of 13C-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 of status by the other diagnostic methods.
  
  
  RESULTS
  One 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 delta units had the same high diagnostic accuracy. The area under the receiver operating characteristic curve was 0.94. No adverse effects were reported.
  
  
  CONCLUSIONS
  Urea breath test using 50 mg of urea is sufficient and accurate for the diagnosis of infection in children. Use of a small test dose significantly lowers the cost of the test.
authors.affiliation: Paediatry Service, Hospital San Rafael, Rey Juan Carlos University of Madrid, Madrid, Spain. alfonsocanete@yahoo.es
authors.forename: Alfonso
authors.initials: A
authors.lastname: Canete
authors.forename: Yamil
authors.initials: Y
authors.lastname: Abunají
authors.forename: Guillermo
authors.initials: G
authors.lastname: Alvarez-Calatayud
authors.forename: Mercedes
authors.initials: M
authors.lastname: DeVicente
authors.forename: José A
authors.initials: JA
authors.lastname: González-Holguera
authors.forename: María
authors.initials: M
authors.lastname: Leralta
authors.forename: José M
authors.initials: JM
authors.lastname: Pajares
authors.forename: Javier P
authors.initials: JP
authors.lastname: Gisbert
mesh_terms: D000293:Adolescent; D001944:Breath Tests; D002247:Carbon Isotopes; D002648:Child; D002675:Child, Preschool; D005260:Female; D005773:Gastroscopy; D016481:Helicobacter Infections / Q000175:diagnosis* / Q000382:microbiology; D016480:Helicobacter pylori / Q000302:isolation & purification*; D006801:Humans; D008297:Male; D013058:Mass Spectrometry; D011446:Prospective Studies; D012372:ROC Curve; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014508:Urea
chemical_list: D002247:Carbon Isotopes; D014508:Urea