SERUM C-13-BICARBONATE ASSAY FOR THE DIAGNOSIS OF GASTRIC HELICOBACTER-PYLORI INFECTION AND RESPONSE TO TREATMENT

Background & Aims: Current serological tests for Helicobacter pylori ( HP) infection are not useful in assessing active infection or eradicat ion. The feasibility, sensitivity, and specificity of serum C-13-bicar bonate (C-13-HCO3) measurement in determining gastric HP before and af ter eradication by antibiotics were investigated. Methods: Twenty-seve n symptomatic patients underwent endoscopy, biopsy, and CLOtest. Patie nts then consumed a C-13-urea-rich meal; serum was collected before an d 1 hour after meal ingestion for quantitative determination of C-13 b y mass spectrometry. Postprandial fractional elevation of C-13 (Delta( 13)C-HCO3) was correlated with endoscopy, histology, and CLOtest at ba seline and at 4 and 8 weeks after therapy. Results: Delta(13)C-HCO3 +/ - SEM was 17.02 +/- 2.94 in HP-positive patients and 2.77 +/- 044 in H P-negative patients (P < 0.0001). In HP-positive patients who responde d 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 < 0.0 01). The overall sensitivity of this method was 90.6% (95% confidence interval, 74.9-98.0), and its specificity was 85.7% (95% confidence in terval, 42.1%-99.6%). Delta(13)C-HCO3 correlated positively with the d egree of histological gastritis and the number of HP organisms. Conclu sions: Serum C-13-HCO3 analysis is a novel, simple, and noninvasive me thod for diagnosis and assessment of eradication of HP infection.