| Along with the economic development, the incademe of childhood obese is increasing rapidly world wild.In China, the epidemic of childhood obesity is still at the early stage, but the growth rate of it increases very fast in many districts. The results of some researches have showed that with the increase of the incidence of obesity, the incidence of precocious puberty in children is also increased.Some studies showed that simple obesity children have higher blood leptin level. Leptin is secreted by fat cell and has effects in central and peripheral region, not only participates in energy metabolism, but also regulate the hormonal changes, and is closely related with obesity, sexual development and reproductive functions. There are evidences reveal that precocious puberty girls'BMI value is higher than that of the normal development ones, and the normal development ones'BMI value is higher than that of the sexual development delay ones, which implys that simple obesity may lead to precocious puberty in girls. Some people believed that there is close relationship between childhood obesity and precocious puberty, Leptin can activate HPGA and trigger the start of pubertal when the nutritional status satisfies individuals'reproductive needs. As the common material of obesity and precocious puberty, leptin becomes a research hotspot in recent years. Whether the high leptin level in obese children plays an important role in the development of precocious puberty. There are not sure that the relationships of leptin among precocious puberty, sex hormones. The relationship between obesity and precocious puberty and function approach of leptin in obesity children still needs to be further studied.ObjectivesTo investigate the prevalence of childhood obesity and precocious puberty in Zhengzhou, explore the relationship between obesity and precocious puberty, understand the levels of leptin and sex hormones, and study their interrelations in precocious puberty children.Methods8750 children from 3 to 12 years old were selected from Zhengzhou by stratified and cluster sampling. All the individuals selected were medical examined, and the data were analyzed by descriptive statistics, chi square tests, tendency tests; 78 girls with precocious puberty and 78 girls who aren't with precocious puberty as control group were collected from Children's hospital of Zhengzhou city. All the objects'bone age and sex hormones were examined and analyzed by paired-sample T tests and Spearman correlations. a=0.05.Results1 The detection rates of overweight, obesity and precocious puberty were 11.0%, 4.2% and 0.7% respectively in Zhengzhou region, and there were gender differences. The detection rates of overweight (12.0%,12.1%) and obesity (6.3%,5.1%) in boys were higher than those in girls (9.4%,9.9%,2.6%,2.0%), and the detection rates of precocious puberty in boys (0.2%,0.3%) were lower than that in girls (1.3%,1.5%) in both city and suburbs of Zhengzhou region.2 The detection rates of precocious puberty in overweight and obesity children (1.4 %) was higher than that of the normal children (0.6%), and the detection rates of precocious puberty in overweight and obesity girls (3.1%) was much higher than that of the normal girls (1.1%), while there were no significances in boys. With the increase of the degree of obesity, the detection rates of precocious puberty were also increased (χ2=10.629, p=0.001); There were age differences in detection rates of precocious puberty in girls, detection rates of precocious puberty of 3-8 age group (3.5%) was higher than that of the 8-12 age group (0.3%).3 The levels of body height, weight, BA, BMI, LEP, LH, FSH and E2 in girls with precocious puberty were higher than those of the control group, while the level of T was lower in precocious puberty group than that in the control group (p<0.05).4 The results of correlation analysis showed that there were positive correlations between LEP and LH, FSH, BMI, BA and BMI, T, LH, FSH, E2, while there were no correlations between LEP and E2, T. Compared with BA, the correlations between LEP and BMI, LH, FSH were stronger. In the control group, there was only positive correlation between BA and T. After controlling BMI, the results of partial correlation analysis showed that there were positive correlations between LEP and FSH, BA and T in precocious puberty girls, while there was only positive correlation between BA and LH in control group.5 There were positive correlations between LEP and BA in the two groups before and after controlling BMI, and after controlling BMI, the correlations of LEP and BA (r=0.484, r=0.300) were weaker than before (r=0.606, r=0.335). Howere, no matter before and after controlling BMI, the correlations between LEP and BA in precocious puberty girls were stronger than that in the control group.Conclusions1 There were sex differences in the detection rates of overweight, obesity and precocious puberty. And in both citys and suburbs, the boys'detection rates of overweight, obesity were higher than girls', but the detection rates of precocious puberty were opposite.2 There was close relationship between obesity and precocious puberty, and the detection rate of precocious puberty among the overweight and obese children was higher than normal weight children. with the increasing of the degree of obesity, the detection rates of precocious puberty also increased among girls.3 There were close relationships between BMI and bone age, leptin, sex hormones of the precocious children. But the relationships do not entirely depended on BMI, it implys that there are independing correlations among bone age, leptin, sex hormones.4 Compared with the control group, the correlations between bone age, leptin and sex hormones in girls with precocious puberty were stronger. Compared with the bone age, there was a stronger correlation between leptin and sex hormones in girls with precocious puberty, It suggests that high leptin level may play an important role in the development of precocious puberty.
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