Extension Study of Pegylated Somatropin to Treat Growth Retardation Caused by Endogenous Growth Hormone Deficiency in Children

Inclusion Criteria: * Children has completed all visits and therapy in previous phase IV study; * Investigators evaluate subjects could continue growth hormone therapy; * Subjects is willing and able to cooperate to complete scheduled visits, treatment plans and laboratory tests and other procedures, to sign informed consent. Exclusion Criteria: * Children with epiphyseal closure; * Children is near the adule final height, that is, growth rate≤ 2 cm / year or bone age ≥ 14 years old for girls, bone age ≥ 16 years old for boys; * Dysfunction of liver and kidney (ALT\> 2 times the upper limit of normal, Cr\> upper limit of normal); * Patients with known hypersensitivity to PEG-Somatropin or Somatropin or any other components of the study product; * Patients with severe cardiopulmonary or hematological diseases, a current or past history of malignant tumors, immunodeficiency diseases, or mental diseases; * Patients with diabetics; * Patients with congenital bone dysplasia or scoliosis; * Patients took drugs that would influence the efficacy and safety of PEG-Somatropin after phase IV study and before screening for this extension study; * Other conditions in which the investigator preclude enrollment into the study.