Prospective, Multicenter Study of the Efficacy and Tolerance of Tacrolimus on Refractory Nephrotic Syndrome (RNS)

Inclusion Criteria: 1. Subjects of either sex, 14-65 years of age; 2. Diagnosis of Nephrotic syndrome with hypoalbuminemia (\<3.0g/dl) and heavy proteinuria (\> 3.5g/24hr); 3. Provision of written informed consent by subject or guardian; 4. Refractory nephrotic syndrome: Steroid resistant: Persistence of proteinuria despite prednisone therapy 1mg/kg/d for 16 weeks; Steroid dependent: NS recurs when steroid dosage decease.Twice within 6 months, and 3 times within 1 year. Exclusion Criteria: 1. Inability or unwillingness to provide written informed consent ; 2. Known hypersensitivity or contraindication to tacrolimus, cyclophosphamide, azathioprine, corticosteroids; 3. Usage of immunosuppression therapy (MMF, CTX, CysA, MTX ect) for more than 1 week within 1 month prior to first randomization; 4. Pregnancy, nursing or use of a non-reliable method of contraception; 5. Continuous dialysis starting more than 2 weeks before randomization into the induction phase and/or continuous dialysis with an anticipated duration of more than 8 weeks; 6. Previous kidney transplant or planted transplant; 7. Scr \> 4mg/dl (353umol/L); 8. Active hepatitis, with liver dysfunction; 9. Diagnosed DM; 10. Participation in another clinic trial and/or receipt of investigational drugs within 4 weeks prior to screening .