ISS refers to short stature that is less than 2 standard deviations of the average height of normal children of the same sex and age; excluding short stature caused by GHD, small for gestational age, systemic diseases, other endocrine diseases, nutritional diseases, chromosomal abnormalities, skeletal dysplasia, and psycho-emotional disorders. In essence, it is a general term for a group of diseases of short stature whose etiology is not yet known.
Sixty to 80% of children with short stature below -2s meet the definition of ISS, and the definition includes physical pubertal delay and familial short stature. Therefore, ISS is an exclusive diagnosis, and it is important to exclude other causes of short stature based on the patient’s medical history, family history, clinical presentation, physical examination, and relevant laboratory tests during the diagnosis process.
At present, patients diagnosed with ISS may have reduced GH secretion, SHOX gene defect, GH promoter dysfunction, GH molecular abnormality, GH signaling pathway genetic defect, etc. With the widespread clinical application of genetic analysis techniques, more GH-IGF1 axis-related genetic abnormalities may be identified in children with ISS.
The treatment criteria for ISS are based on growth indicators, and there are no biochemical indicators to determine whether to initiate ISS treatment. height indications for ISS treatment vary depending on the country/region and clinical parameters.
In the United States, the treatment criteria for ISS are: -2.25s (<1.2 percentile) below the mean height of a healthy population of the same sex and age; -2 to -3 SDS below the mean height as recommended by the Growth Hormone Research Society, the Lawson Wilkins Pediatric Endocrine Society, and the European Society of Endocrinology, and the recommended age for starting treatment is 5 years to early adolescence; Most of the foreign data of ISS patients rhGH treatment you say the age is 3~4 years old or more. Children with ISS who are recommended to be treated with rhGH in China should meet the following conditions: ① height is -2s behind the average height of normal healthy children of the same age and sex; ② length and weight at birth are in the normal range for children of the same gestational age; ③ systemic diseases, other endocrine diseases, nutritional diseases, chromosomal abnormalities, skeletal dysplasia, psycho-emotional disorders and other causes of short stature are excluded; ④ GH peak in GH drug provocation test was ≥10ug/L; ⑤ The age of starting treatment was 5 years.