Inclusion Criteria:  18 years or older; Isolated thrombocytopenia (platelet count of less than 100×10^9/L); Normal leukocyte and erythrocyte counts according to routine blood tests; Did not receive any medication for thrombocytopenia for 6 months.  Exclusion Criteria:  Secondary ITP such as drug-associated thrombocytopenia; Thrombocytopenia caused by viral infection (HIV, Hepatitis B virus or Hepatitis C virus); Nursing or pregnant women; Severe dysfunction of the heart, kidney, lung or liver; Active or previous malignancy; Patients with other diseases were undergoing treatment with immunosuppressants; Myelodysplastic disorder or myelofibrosis; Patients who were undergoing first - or second-line therapy for thrombocytopenia within 6 months.