Volatile Organic Compounds (VOCs) of Exhaled Breath in Patients With GI Bleeding

Inclusion Criteria: * Adults aged between 20 and 80 * Low possibility of gastrointestinal bleeding was proven by esophagogastroduodenoscopy and colonoscopy which were performed within 1 year. * NSAID non-user (within 1 months before the date of inclusion) Exclusion Criteria: * Diagnosis of malignancy diagnosed within 5 years * Past medical history of chronic liver disease, chronic kidney disease, chronic lung disease, chronic bronchial disease, asthma * Surgical history of any kind of gastrectomy * Surgical history of any kind of lung resection which could impact the patient's lung function.