Serum Gastrin Predicts Hydrogen-Producing Small Intestinal Bacterial Overgrowth in Patients With Abdominal Surgery: A Prospective Study

OBJECTIVES: Small intestinal bacterial overgrowth (SIBO) might be associated with a history of abdominal surgery. We aimed to evaluate the prevalence of SIBO and to investigate serum gastrin and pepsinogen as predictors of SIBO in patients with a history of hysterectomy, gastrectomy, or cholecystectomy. METHODS: This prospective study surveyed 146 patients with a history of hysterectomy, gastrectomy, or cholecystectomy, and 30 healthy controls, who underwent a hydrogen (H(2))-methane (CH(4)) glucose breath test (GBT) for SIBO. Serum pepsinogen I and II and gastrin levels were reviewed. RESULTS: GBT positivity (+) was significantly higher in patients with histories of abdominal surgery than that in in controls (37.6% vs 13.3%, P < 0.01). Among GBT+ patients, 36.0% (18/50), 96.2% (25/26), and 17.1% (12/70) were in the hysterectomy, gastrectomy, and cholecystectomy groups, respectively. Among the GBT subtypes, 43.6% (24/55), 10.9% (6/55), and 45.5% (25/55) of patients were in the GBT(H(2))+, GBT(CH(4))+, and GBT(mixed)+ groups, respectively. The gastrectomy group had significantly more GBT+ or GBT(H(2))+ patients than the other surgical groups. Gastrin levels were higher in GBT(H(2))+ patients and lower in GBT(CH(4))+ patients than those in GBT− patients. Previous gastrectomy and elevated gastrin levels were independent predictive factors of GBT(H(2))+. DISCUSSION: SIBO is not uncommon in patients with histories of abdominal surgeries, but it is more common in patients who have undergone gastrectomy. Serum gastrin level could be a serologic predictor of H(2)-producing SIBO. The relationship between serum gastrin and SIBO requires further research.