I. Subjects: 462 healthy children, 205 females and 257 males, aged 1 month to 14 years, who came to our health check-up clinic from October 2002 to October 2003. The children were naturally grouped into 30 age groups according to sex and age, and then regrouped into 12 age groups after combining age groups with similar measurement results or those with a smaller number of cases. Except for neonatal physiological jaundice, all other selected subjects were free of cardiac, hepatic, renal and endocrine disorders.
Methods: When blood specimens were collected for the formal physical examination, 2-3 ml of fasting venous blood was collected from the selected children, and the serum was separated within 4 hours and stored in a -20bC refrigerator for testing. The reagents were original reagents provided by DPC, USA, and the instrument was IMMULITE luminometer from DPC, USA.
Statistical analysis: standard deviation method Most developmental indicators of normal children are normally distributed, and the range of this normal distribution is related to the mean and standard deviation. That is, 68.3% of children’s developmental levels were within the range of the mean plus or minus 1 standard deviation, 95.4% within the range of the mean plus or minus 2 standard deviations, and 99.7% within the range of the mean plus or minus 3 standard deviations. Therefore, it is more reasonable to use the mean and standard deviation to evaluate the growth and development level of children than to use the mean alone.
IV. Results: The growth and development process of children is divided into fetal period, neonatal period, infant and toddler period, preschool period, school age and adolescent period. We measured the levels of sex hormones in children from infancy to puberty as the main study subjects.
The age range and staging criteria of puberty are not yet uniform at home and abroad. However, the division of the pubertal development process into early and late stages is considered to be consistent. We measured the levels of sex hormones in normal children at each stage to provide an objective basis for the age of initiation of pubertal development in children.
The results of T and T2 measured by the natural age grouping of girls were subdivided into 6 groups with similar results (no significant difference) according to the test results for clinical application, since the basal values of hormones in children at prepubertal and pubertal stages often overlap.