Patients who have heartburn or regurgitation more than 2 times/week for at least 1 month were defined as having GERD and patient without any reflux symptoms served as controls.The exclusion criteria were 1) pregnancy, 2) cirrhosis or presence of gastroesophageal varices, 3) gastrointestinal hemorrhage, 4) angina pectoris, 5) allergy to PPI, 6) high risk or contraindication for endoscopy, 7) chronic cough, laryngitis, asthma.