Serum 13C-bicarbonate assay for the diagnosis of gastric Helicobacter pylori infection and response to treatment

Abstract

Background & aims: 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.