Hypersenstivity to Acid in Ulcer-like Functional Dyspepsia

OBJECTIVES The mechanism of pain sensation in patients with ulcer-like functional dyspepsia is unclear and there are no guidelines for its treatment. Whilst much research and many pharmacological treatments have provided symptomatic relief of ulcer-like functional dyspepsia through control of acid secretion, the role of acid in ulcer-like functional dyspepsia is unknown. We carried out this study to investigate the role of hypersensitivity to acid in the sensation of pain in ulcer-like functional dyspepsia by direct administration of acid into stomach. METHODS Twelve patients with ulcer-like functional dyspepsia (5 male, 7 female, mean age 41.0 years old, 7 with mild chronic superficial gastritis, 2 with metaplastic gastritis and 3 with normal endoscopic findings) and seven healthy control subjects (3 male, 4 female, mean age 36.0 years old, 7 with normal endoscopic findings) participated in the study. After overnight fasting, a nasogastric sump tube was inserted and its tip was positioned in the antrum under fluoroscopic guidance. Normal saline or 0.1N hydrochloric acid was administered in random and single blind cross over fashion. The test was considered positive only if similar pain developed-similar to that experienced by the patient under nonstudy condition- during the administration. RESULTS Five patients (41.7%) developed pain with 0.1N hydrochloric acid administration, but none with normal saline (p < 0.05). None of the healthy controls developed pain upon administration of 0.1N hydrochloric acid or normal saline. CONCLUSION We suggest that acid hypersensitivity plays a role in the sensation of pain in ulcer-like functional dyspepsia.