title: Do patients need to fast for a 13C-urea breath test?
abstract: OBJECTIVE
  The 13C-urea breath test (13C-UBT) is a useful non-invasive method of diagnosing Helicobacter pylori infection. One of its limitations, however, is that patients have to fast for 4 h before testing. We have compared the accuracy of a non-fasting 13C-UBT (NF13C-UBT) with a fasting 13C-UBT (F13C-UBT) test and against a gold standard.
  
  
  METHODS
  An unblinded prospective crossover study.
  
  
  METHODS
  H. pylori status was assessed by histology, culture and rapid urease test. Patients were defined as H. pylori positive if two or more tests gave a positive result and negative if all tests were negative. H. pylori status was indeterminate if only one test gave a positive result. Following endoscopy patients had a F13C-UBT and then a further NF13C-UBT up to 14 days later after eating two slices of toast with jam or honey and tea or coffee.
  
  
  RESULTS
  Of the 222 patients recruited to the study, 123 were gold standard H. pylori positive and 94 were negative with five patients having indeterminate status. Compared to this gold standard the NF13C-UBT had a 98% sensitivity and 96% specificity and the F13C-UBT had a 96% sensitivity and 97% specificity. The NF13C-UBT and F13C-UBT agreed in 217/222 (98%) cases.
  
  
  CONCLUSIONS
  Relaxation of the fasting state does not reduce the accuracy of the 13C-UBT, making this test more convenient for patients.
authors.affiliation: Centre for Digestive Diseases, Leeds General Infirmary, UK.
authors.forename: P
authors.initials: P
authors.lastname: Moayyedi
authors.forename: D
authors.initials: D
authors.lastname: Braunholtz
authors.forename: E
authors.initials: E
authors.lastname: Heminbrough
authors.forename: M
authors.initials: M
authors.lastname: Clough
authors.forename: D S
authors.initials: DS
authors.lastname: Tompkins
authors.forename: N P
authors.initials: NP
authors.lastname: Mapstone
authors.forename: S
authors.initials: S
authors.lastname: Mason
authors.forename: A C
authors.initials: AC
authors.lastname: Dowell
authors.forename: I D
authors.initials: ID
authors.lastname: Richards
authors.forename: D M
authors.initials: DM
authors.lastname: Chalmers
authors.forename: A T
authors.initials: AT
authors.lastname: Axon
mesh_terms: D001706:Biopsy; D001944:Breath Tests / Q000379:methods*; D002247:Carbon Isotopes; D018592:Cross-Over Studies; D005215:Fasting; D005753:Gastric Mucosa / Q000378:metabolism; D016481:Helicobacter Infections / Q000175:diagnosis*; D016480:Helicobacter pylori / Q000302:isolation & purification*; D006801:Humans; D012680:Sensitivity and Specificity; D014508:Urea; D014510:Urease / Q000378:metabolism
chemical_list: D002247:Carbon Isotopes; D014508:Urea; D014510:Urease