This study aims to explore the optimal dose of pegylated recombinant human growth hormone (PEG-rhGH) injection to treat children with idiopathic short stature (ISS), evaluate its safety and efficacy, and provide scientific and reliable evidence for the medication dosage in Phase III clinical study.

Inclusion Criteria:

• Boys are between 4 and 9 years of age and girls are between 4 and 8 years of age.
• Height <-2 SD for chronological age.
• Growth velocity<5.0 cm/yr.
• GH peak concentration ≥10.0 ng/mL in two different stimulation tests.
• The difference of bone age (BA) and chronological age (CA) is within -2 to +2.
• IGF-1 concentration is between -2 SDS to +2 SDS.
• Prepubertal Status(Tanner Stage I).
• Birth weight within the normal range.
• Growth hormone treatment-naive.
• Subjects are willing and able to cooperate to complete scheduled visits, treatment plans and laboratory tests and other procedures, to sign informed consent.

Exclusion Criteria:

• Subjects with abnormal liver and kidney functions (ALT > upper limit of normal value; Cr > upper limit of normal value).

• Subjects are positive for anti-HBc, HbsAg or HbeAg in Hepatitis B virus tests.

• Subjects with known highly allergic constitution or allergy to investigational product or its excipient.

• Subjects with systemic chronic disease and immune deficiency.

• Patients diagnosed with tumor.

• Patients with mental disease.

• Patients with other types of abnormal growth and development.

  1. Growth hormone deficiency (GHD) (confirmed by GH stimulation test);
  2. Turner syndrome (confirmed by karyotype test of girls);
  3. Noonan syndrome (hypertelorism, pectus carinatum, hypophrenia, frequently with skin disease and congenital heart disease, missense mutation of the protein tyrosine phosphatase, non-receptor type 11 (PTPN11) gene on chromosome 12 for half of the patients, for both male and female patients);
  4. Laron sydrome (confirmed by IGF-1 generation test);
  5. Small for gestational age ( the birth height or weight is below the tenth percentile or 2 SD, with catch-up growth uncompleted at 2 years old).

• Growth disorders caused by malnutrition or hypothyroidism (thyroid function test).

• Congenital skeletal abnormalities or scoliosis, claudication.

• Subjects with impaired glucose regulation (IGR) (including impaired fasting glucose (IFG) and/or impaired glucose tolerance (IGT) ) or diabetes).

• Subjects with abnormal electrolyte, blood gas analysis (vein), creatine kinase.

• Subjects who took part in other clinical trials within 3 months.

• Subjects who received medications which may interfere GH secretion or GH function, or other hormones within 3 months (such as sex steroids, glucocorticoids, etc.).

• For patients with potential high tumor risks such as tumor markers exceed normal range and some other relative information, they may be excluded from the treatment.

• Other conditions which is inappropriate for this study in the opinion of the investigator.