Phase 1: To evaluate the safety and efficacy of 0.05mg/kg/d of rhGH (Jintropin®) in the treatment of children with idiopathic short stature (ISS) in 52 weeks.

Phase 2: To evaluate the safety and efficacy of rhGH (Jintropin®) in the treatment of children with ISS in 2 years

Inclusion Criteria:

• Boys are between 4 and 10 years old age and girls are between 4 and 9 years old age;
• Height <-2.25 SD (Standard deviation) for chronological age;
• GH (Growth hormone) peak concentration ≥10.0 ng/mL in GH stimulation tests;
• The bone age (BA) ≤chronological age (CA)+6 months;
• Prepubertal Status (Tanner Stage I);
• Birth weight within the normal range;
• Growth hormone treatment-naive;
• Participants are willing and able to cooperate to complete scheduled visits, treatment plans and laboratory tests and other procedures, to sign informed consent.

Exclusion Criteria:

• Participants with abnormal liver and kidney functions (ALT > upper limit 1.5 times of normal value; Cr > upper limit of normal value);

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

• Participants with known highly allergic constitution or allergy to investigational product or its excipient;

• Participants with systemic chronic disease and immune deficiency;

• Participants diagnosed with tumor, or with potential high tumor risks such as tumor markers exceed normal range and some other relative information may be excluded from the treatment;

• Participants with mental disease;

• Participants 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 participants, for both male and female participants);
  4. Laron syndrome (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);
  6. Growth disorders caused by malnutrition or hypothyroidism (thyroid function test).

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

• BMI (Body mass index) ≥22kg/m²;

• Congenital skeletal abnormalities or scoliosis, claudication;

• Participants who took part in other clinical trials within 3 months;

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

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