H. Pylori Eradication for Moderate ITP

Inclusion Criteria: * Age ≥ 19 years * Persistent or chronic ITP patients defined by international working group * 30 X 10\^9/L ≤ platelet level ≤ 80 X 10\^9/L * H. pylori infection should be confirmed by at least one of tests: urea breath test (UBT), CLO, stool H. pylori Ag, H. pylori in gastric tissue (reported by a trained pathologist) * No history of any ITP treatment for the past 3 months * No previous history of H. pylori eradication treatment * Patients who voluntarily participate in this study and with informed consents Exclusion Criteria: * patients who have any cause of thrombocytopenia such as HIV, HCV infection, lymphoproliferative disease, malignant neoplasm, liver disease, definite SLE and other autoimmune diseases, drugs, MDS and leukemia * uncontrolled hypothyroidism or hyperthyroidism * active bleeding for the past 3 months or history of hemorrhagic gastric ulcer or brain hemorrhage * active infection * patients who are taking anticoagulant or aspirin * patients with penicillin allergy or side effects of macrolide * patients who are taking mizolastine, terfenadine, cisapride, pimozide, astemizole, ergot alkaloid and its derivatives (ergotamine and dihydroergotamine), bepridil or atazanavir * patients who have known allergy or severe side effect on study drugs * pregnant or lactating women