title: Stability of (13) C-Urea Breath Test Samples Over Time in the Diagnosis of Helicobacter pylori.
abstract: BACKGROUND
  The accuracy and repeatability of breath test in the diagnosis of Helicobacter pylori infection have not been adequately investigated. Although it has been shown that storage for long periods does not affect the analysis results, no data are available on the effect of repetitive testing. In this study, our aim was to evaluate the repeatability of the analyses of breath samples at room temperature.
  
  
  METHODS
  A total of 202 positive breath samples were collected in duplicates, before and after administration of 75 mg (13) C- urea dissolved in 100 ml of orange juice. Breath test results were expressed as delta (13) CO2 . The cut-off value was 3.5 parts per thousand. Each sample was analyzed in a mass spectrometer 7, 14, 21, and 28 days after collection. The accuracy calculation was based on the comparison of the delta (13) CO2 obtained in the three consecutive weeks following the first test run to the delta (13) CO2 obtained in the first test run.
  
  
  RESULTS
  Two hundred (99%), 197 (97.52%), and 196 (97%) of the 202 samples tested positive in the second, third, and fourth test runs, respectively. The accuracy of the delta (13) CO2 was 98.6%, 99.2%, and 96.7% in the three consecutive runs, respectively.
  
  
  CONCLUSIONS
  Short-term storage of 1 month does not affect sample stability or the results of (13) C-urea breath tests in up to three consecutive repeats.
authors.affiliation: Gastroenterology Laboratory, Rabin Medical Center - Beilinson Hospital, Petah Tikva, Israel.|Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Tsachi Tsadok
authors.initials: TT
authors.lastname: Perets
authors.affiliation: Gastroenterology Laboratory, Rabin Medical Center - Beilinson Hospital, Petah Tikva, Israel.
authors.forename: Einav
authors.initials: E
authors.lastname: Shporn
authors.affiliation: Department of Gastroenterology, Rabin Medical Center - Beilinson Hospital, Petah Tikva, Israel.|Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Doron
authors.initials: D
authors.lastname: Boltin
authors.affiliation: Department of Gastroenterology, Rabin Medical Center - Beilinson Hospital, Petah Tikva, Israel.|Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Ram
authors.initials: R
authors.lastname: Dickman
authors.affiliation: Department of Gastroenterology, Rabin Medical Center - Beilinson Hospital, Petah Tikva, Israel.|Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Yaron
authors.initials: Y
authors.lastname: Niv
mesh_terms: D001944:Breath Tests / Q000379:methods*; D002247:Carbon Isotopes; D016481:Helicobacter Infections / Q000175:diagnosis* / Q000382:microbiology*; D016480:Helicobacter pylori / Q000502:physiology*; D006801:Humans; D015203:Reproducibility of Results; D013997:Time Factors; D014508:Urea / Q000378:metabolism*
chemical_list: D002247:Carbon Isotopes; D014508:Urea
keywords: 13C-urea breath test; H. pylori diagnosis; IRMS; reproducibility; test accuracy