Oseltamivirphosphate is hydrolysed to its active metabolite-the free carboxylate of oseltamivir. Oseltamivir is a neuraminidase inhibitor, serving as a competitive inhibitor of the activity of the viral neuraminidase (NA) enzyme upon sialic acid, found on glycoproteins on the surface of platelets. By blocking the activity of the enzyme, oseltamivir may prevent platelet destruction in liver.The project was undertaking by Qilu Hospital of Shandong University and other 4 well-known hospitals in China. In order to report the efficacy and safety of oseltamivirphosphate combined with high-dose dexamethasone for the treatment of immune thrombocytopenia (ITP) with high platelet desialylation level, compared to high-dose dexamethasone therapy.

The investigators are undertaking a parallel group, multicentre, randomised controlled trial of 50 newly diagnosed ITP adult patients with high platelet desialylation level from 5 medical centers in China. One part of the participants are randomly selected to receiver HD-DXM (orally at 40 mg daily for 4d) combined with oseltamivir (orally at 75 mg twice for 10d), the others are selected to receive HD-DXM (orally at 40 mg daily for 4d ) alone. If platelet counts remained <30×109/L or there were bleeding symptoms by day 10, another 4-day course of HD-DXM was given (days 10-14).For the combination arm, patients with an initial response relapsed during the follow-up period, oseltamivir retreatment could be given for another 10 days at the discretion of the physician's advice and patients' will.

Platelet count, bleeding , platelet desialylation level and other symptoms were evaluated before and after treatment. Adverse events are also recorded throughout the study. In order to report the efficacy and safety of oseltamivirphosphate combining with high-dose dexamethasone therapy compared to high-dose dexamethasone for the treatment of adults with newly diagnosed ITP .

Inclusion Criteria:

• newly diagnosed ITP patients need of treatment(s) to minimize the risk of clinically significant bleeding primary ITP confirmed by excluding other supervened causes of thrombocytopenia

Exclusion Criteria:

• pregnancy hypertension cardiovascular disease diabetes liver and kidney function impairment HCV, HIV, HBsAg seropositive status patients with systemic lupus erythematosus and/or antiphospholipid syndrome