title: Serum 13C-bicarbonate assay for the diagnosis of gastric Helicobacter pylori infection and response to treatment.
abstract: OBJECTIVE
  Current serological tests for Helicobacter pylori (HP) infection are not useful in assessing active infection or eradication. The feasibility, sensitivity, and specificity of serum 13C-bicarbonate (13C-HCO3) measurement in determining gastric HP before and after eradication by antibiotics were investigated.
  
  
  METHODS
  Twenty-seven symptomatic patients underwent endoscopy, biopsy, and CLOtest. Patients then consumed a 13C-urea-rich meal; serum was collected before and 1 hour after meal ingestion for quantitative determination of 13C by mass spectrometry. Postprandial fractional elevation of 13C (delta 13C-HCO3) was correlated with endoscopy, histology, and CLOtest at baseline and at 4 and 8 weeks after therapy.
  
  
  RESULTS
  delta 13C-HCO3 +/- SEM was 17.02 +/- 2.94 in HP-positive patients and 2.77 +/- 044 in HP-negative patients (P < 0.0001). In HP-positive patients who responded to therapy, the mean change was initially 20.5 +/- 3.1, 3.2 +/- 0.9 1 month after therapy, and 2.8 +/- 0.4 2 months after therapy (P < 0.001). The overall sensitivity of this method was 90.6% (95% confidence interval, 74.9-98.0), and its specificity was 85.7% (95% confidence interval, 42.1%-99.6%). delta 13C-HCO3 correlated positively with the degree of histological gastritis and the number of HP organisms.
  
  
  CONCLUSIONS
  Serum 13C-HCO3 analysis is a novel, simple, and noninvasive method for diagnosis and assessment of eradication of HP infection.
authors.affiliation: Gastroenterology Section, Palo Alto Veterans Affairs Health Care System, California 94304, USA.
authors.forename: M J
authors.initials: MJ
authors.lastname: Kim
authors.forename: R
authors.initials: R
authors.lastname: Michener
authors.forename: G
authors.initials: G
authors.lastname: Triadafilopoulos
mesh_terms: D000658:Amoxicillin / Q000627:therapeutic use; D001639:Bicarbonates / Q000097:blood*; D001729:Bismuth / Q000627:therapeutic use; D002247:Carbon Isotopes; D017291:Clarithromycin / Q000627:therapeutic use; D004359:Drug Therapy, Combination; D005753:Gastric Mucosa / Q000382:microbiology / Q000473:pathology; D005756:Gastritis / Q000097:blood / Q000175:diagnosis / Q000188:drug therapy / Q000382:microbiology*; D016481:Helicobacter Infections / Q000097:blood / Q000175:diagnosis* / Q000188:drug therapy; D016480:Helicobacter pylori; D006801:Humans; D008297:Male; D013058:Mass Spectrometry; D008795:Metronidazole / Q000627:therapeutic use; D008875:Middle Aged; D009853:Omeprazole / Q000627:therapeutic use; D012680:Sensitivity and Specificity; D013752:Tetracycline / Q000627:therapeutic use
chemical_list: D001639:Bicarbonates; D002247:Carbon Isotopes; D008795:Metronidazole; D000658:Amoxicillin; D013752:Tetracycline; D017291:Clarithromycin; D009853:Omeprazole; D001729:Bismuth