The efficacy of genetically recombinant human growth hormone (hereafter referred to as growth hormone) in treating short stature in children has been confirmed, but at what age is it most appropriate to administer the drug to children with short stature? When is the best time to use the drug? This is a question of great concern to parents. Theoretically, as long as the bone marrow of the child has not healed, growth hormone can be applied to achieve the purpose of height growth, and the earlier the drug is administered, the greater the potential to promote height growth. However, in clinical practice, different diseases have their own characteristics, which are described below. Growth hormone deficiency: Short stature due to insufficient secretion of growth hormone in the anterior pituitary gland is the preferred indication for growth hormone therapy. Treatment should be started at an early age, usually from the age of four or five. The course of treatment should be long and should last until the epiphysis is fused. The course of treatment should be 3 months, and the decision to continue is based on the response to treatment and the family’s financial situation. Turner syndrome: also known as primary ovarian dysplasia. Treatment should be started at an early age, usually at the age of 5. Growth hormone alone can be used until the age of 9 to 10 years, and thereafter it can be used simultaneously with protein synthesis hormone to improve the height. If the bone age is close to 12 years old at the time of diagnosis, it is advisable to postpone estrogen replacement therapy and use growth hormone first, and then use estrogen to induce puberty after reaching a satisfactory height. When the child is older than 14 years old and the annual growth rate is less than 2.5 cm, then treatment can be terminated. Chronic renal failure: Chronic renal failure due to various causes with severe growth retardation should be treated with growth hormone for at least 6 months. If height growth is satisfactory and bone maturation is not affected, treatment may be continued for 3 years. Short stature due to younger-than-gestational-age children: Postnatal follow-up results show that most younger-than-gestational-age children are able to catch up with full-term children in terms of height and weight. A small percentage of children are still lagging behind in height 2 years after birth, which is an indication for drug use. Generally, treatment is started 2 years after birth, so that the height of the child can catch up with that of a normal child of the same age and then the drug is stopped. It is effective, but the bone age progression needs to be monitored. Hypochondroplasia (ACH) and hypochondroplasia (HCH): ACH is a form of congenital dwarfism, which is characterized by disproportionate body shape and short limbs. In the past, it was thought that the abnormal cartilage did not respond to growth hormone stimulation, but now it is thought that ACH patients do not have abnormal cartilage tissue structure, but rather the cartilage area is thin, so it is possible to stimulate the growth of chondrocytes with growth hormone. HCH: It is one of the types of chondrodysplasia with mild clinical symptoms, showing short limbs and mild anterior convexity of the lumbar spine. Because of the prominent height lag in children, the author believes that the medication can be started from 2 to 3 years of age. Hypophosphatemic rickets (HPR): Also known as familial hypophosphatemia, growth disorders are an important problem in HPR. Growth factor therapy has been reported to significantly promote growth, improve phosphorus conservation, and increase bone mineral and renal hydroxylase activity in children with HPR. The drug can be started if the child has an existing growth disorder, but the effect of long-term treatment on the patient’s final height is inconclusive. Others: including trisomy 21 (DS), congenital dwarf dementia syndrome (Noonan syndrome), hypotonia-hypointelligence-hypogonadism-obesity syndrome (Prader-Willi syndrome), etc., all have varying degrees of short stature, and many have been treated with growth hormone, which has recently accelerated the patient’s height growth, but there is no information on the effect on the patient’s final height. However, there is no information on the improvement of the patient’s final height. Furthermore, these patients are mentally retarded, prone to leukemia, have heart and other organ malformations, and have low glucose tolerance, so great care must be taken when choosing growth hormone therapy. The age of initiation of treatment is also not known.