The project was undertaking by Qilu Hospital of Shandong University and other well-known hospitals in China. In order to study the efficacy and safety of different dose and frequency Recombinant Human thrombopoietin in treating the primary immune thrombocytopenia (ITP)

The investigators are undertaking a parallel group, multicentre, randomised controlled trial of 30 primary ITP adult patients from 3 medical centers in China. They will be randomly assigned in a 1:1:1 ratio into three groups .The patients in group A (total 10 patients) will receive rhTPO at a dose of 300Units/kg ,daily for 14 consecutive days;The patients in group B will receive rhTPO at a dose of 300Units/kg ,one times every other day for 7 times.The patients in group C will receive rhTPO at a dose of 300Units/kg ,daily for 7 consecutive days .All the patients will follow with a flexible dosage depending on platelet count during the following 12 weeks.

Platelet counts, bleeding and other symptoms were evaluated before and after treatment, in order to evaluate the efficacy and safety of different dose and frequency Recombinant Human thrombopoietin in treating the primary immune thrombocytopenia (ITP)

Inclusion Criteria:

1. Subject is ≥18 years old, may be male or female.
2. Diagnosed with ITP meeting the diagnostic criteria for immune thrombocytopenia.
3. Patients who have no response or relapsed after Corticosteroid.
4. To show a platelet count < 30×10^9/L, and with bleeding manifestations.
5. Willing and able to sign written informed consent.

Exclusion Criteria:

1. Received chemotherapy or anticoagulants or other drugs affecting the platelet counts within 3 months before the screening visit.
2. Received second-line ITP-specific treatments (eg, cyclophosphamide, 6-mercaptopurine, vincristine, vinblastine, etc) within 3 months before the screening visit.
3. Received high-dose steroids or IVIG in the 3 weeks prior to the start of the study.
4. Current HIV infection or hepatitis B virus or hepatitis C virus infections.
5. Severe medical condition (lung, hepatic or renal disorder) other than chronic ITP. Unstable or uncontrolled disease or condition related to or impacting cardiac function (e.g., unstable angina, congestive heart failure, uncontrolled hypertension or cardiac arrhythmia)
6. Female patients who are nursing or pregnant, who may be pregnant, or who contemplate pregnancy during the study period.
7. Have a known diagnosis of other autoimmune diseases, established in the medical history and laboratory findings with positive results for the determination of antinuclear antibodies, anti-cardiolipin antibodies, lupus anticoagulant or direct Coombs test.
8. Patients who are deemed unsuitable for the study by the investigator .