title: Twenty-minute fasting version of the US 13C-urea breath test for the diagnosis of H. pylori infection.
abstract: BACKGROUND
  In large-scale multi-center clinical trials, the US 13C-urea breath test (UBT) has proven to have a sensitivity and specificity of approximately 95%. Ingestion of a meal to delay gastric emptying has advantages of increasing the level of signal as well as prolonging the duration of significantly increased 13C excretion, at the expense of requiring 40 to 60 minutes to complete the test. Our aim was to explore the utility of the 13C-UBT with a total duration of 30 minutes or less.
  
  
  METHODS
  After a baseline breath sample was obtained, 125 mg of 13C-urea was given in 100 ml of water, and additional breath samples were taken after 20 and 30 minutes. The results of the UBT were compared to histological assessment, culture, and the rapid urease test. 13C-UBTs were carried out on normal volunteers who underwent gastroscopy during which six mucosal biopsies were taken. Three biopsies were for histological evaluation (Genta stain), two for culture, and one was for agar gel rapid urease testing. The UBT was conducted 2 to 3 days either before or after the endoscopic procedure.
  
  
  RESULTS
  The cutoff value for a positive UBT was enrichment of 2.4 delta/1000 (delta over baseline). Of the 66 tests, 51/1000 were Helicobacter pylori-positive. There were no false positive UBTs and only two false negative UBTs at 20 minutes (sensitivity, 96%; specificity, 100%). At 30 minutes, one other UBT was false negative (gray zone of 2.36/1000) (sensitivity, 94%; specificity, 100%).
  
  
  CONCLUSIONS
  These results suggest that omission of the meal and shortening the duration of the US 13C-UBT to 20 minutes still may maintain excellent specificity and sensitivity of the test.
authors.affiliation: Department of Medicine, Veterans Affairs Medical Center, Houston, TX 77030, USA.
authors.forename: H M
authors.initials: HM
authors.lastname: Malaty
authors.forename: H M
authors.initials: HM
authors.lastname: el-Zimaity
authors.forename: R M
authors.initials: RM
authors.lastname: Genta
authors.forename: P D
authors.initials: PD
authors.lastname: Klein
authors.forename: D Y
authors.initials: DY
authors.lastname: Graham
mesh_terms: D000328:Adult; D000368:Aged; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D001426:Bacterial Proteins / Q000032:analysis / Q000378:metabolism*; D001706:Biopsy; D001944:Breath Tests / Q000379:methods*; D002245:Carbon Dioxide / Q000032:analysis; D002247:Carbon Isotopes; D005069:Evaluation Studies as Topic; D005188:False Negative Reactions; D005189:False Positive Reactions; D005215:Fasting; D005260:Female; D005756:Gastritis / Q000175:diagnosis* / Q000188:drug therapy / Q000378:metabolism / Q000382:microbiology; D016481:Helicobacter Infections / Q000175:diagnosis* / Q000188:drug therapy / Q000378:metabolism / Q000382:microbiology; D016480:Helicobacter pylori / Q000201:enzymology* / Q000302:isolation & purification; D006801:Humans; D008297:Male; D008875:Middle Aged; D012680:Sensitivity and Specificity; D013997:Time Factors; D014508:Urea / Q000493:pharmacokinetics; D014510:Urease / Q000032:analysis / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D002247:Carbon Isotopes; D002245:Carbon Dioxide; D014508:Urea; D014510:Urease