title: Validation of [13C]urea breath test for Helicobacter pylori using a simple gas chromatograph-mass selective detector.
abstract: OBJECTIVE
  Isotope ratio mass spectrometry (IRMS) is the accepted method for accurately measuring the 13CO2:12CO2 ratio in the non-invasive and non-radioactive [13C]urea breath test (13C-UBT) for Helicobactor pylori. The IRMS instrument, an expensive and highly specialized analyser, is rarely available. The objective of this project was to modify and validate the use of a simple bench-top gas chromatograph-mass selective detector (GC-MSD) for 13C-UBT.
  
  
  METHODS
  Breath samples from 71 patients were taken at baseline and 30 min after ingestion of 100 mg [13C]urea. The breath samples were analysed using GC-MSD in the selected ion monitoring mode. The reference 13CO2:12CO2 ratio was from NBS19 obtained from the US National Institute of Standards and Technology. 13CO2:12CO2 ratios of the breath samples were determined. Excess delta per thousand (per mil, delta/thousand) of the 30 min sample over the baseline (deltadelta/thousand) of > or = 6deltadelta/thousand was considered H. pylori positive. Results from 13C-UBT and histology determined blind to each other were compared.
  
  
  RESULTS
  The coefficient of variation of the reference 13CO2:12CO2 ratio was 0.06%. Using histology as the 'gold standard', the sensitivity (97.9%) and specificity (95.8%) of the GC-MSD 13C-UBT were comparable to those of other methods of H. pylori diagnosis.
  
  
  CONCLUSIONS
  A gas chromatograph coupled to a mass selective detector that is available in many analytical and biomedical laboratories can be used for the 13C-UBT. This method will increase the availability and reduce the cost of this non-invasive, non-radioactive diagnostic test.
authors.affiliation: Department of Pharmacology, National University of Singapore, Singapore. phcleehs@nus.edu.sg
authors.forename: H S
authors.initials: HS
authors.lastname: Lee
authors.forename: K A
authors.initials: KA
authors.lastname: Gwee
authors.forename: L Y
authors.initials: LY
authors.lastname: Teng
authors.forename: J Y
authors.initials: JY
authors.lastname: Kang
authors.forename: K G
authors.initials: KG
authors.lastname: Yeoh
authors.forename: A
authors.initials: A
authors.lastname: Wee
authors.forename: B C
authors.initials: BC
authors.lastname: Chua
mesh_terms: D001944:Breath Tests / Q000295:instrumentation* / Q000379:methods; D002245:Carbon Dioxide / Q000032:analysis; D008401:Gas Chromatography-Mass Spectrometry / Q000295:instrumentation; D016481:Helicobacter Infections / Q000175:diagnosis*; D016480:Helicobacter pylori / Q000302:isolation & purification*; D006801:Humans; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014508:Urea / Q000032:analysis*
chemical_list: D002245:Carbon Dioxide; D014508:Urea