The Levels And Characteristics Of Urine Gonadotropin And Gonadal Steroid Hormones In Prepubertal Children With Obesity

Background: The timing of puberty and hormonal parameters during puberty could be affected by obesity.Gonadotropin(Gn)secreted pulsely and gonadal steroid hormones secreted unstablely,and it’s difficult to reflect the actual function of hypothalamic-pituitary-gonadal axis(HPGA)by only once blood sample measurement randomly.However,urine Gn and urine gonadal steroid hormones can reflect the average levels of Gn and gonadal steroid hormones in body at a certain period.Therefore,urine hormones measurement is better to reflect the function of HPGA than blood hormones measurement.What’s more,urine collection has the adventages of non-invasive and convenience,which can improve the compliance for children.In recent years,there are very few literatures about urine Gn and gonadal steroid hormones measured by immunochemiluminometric assay(ICMA)in preschool children with obesity,and the comparison study of obesity rate of preschoolers aged 3~7 years by using four different standards for the definine of childhood obesity.Objective: By measuring urine gonadotropin and gonadal steroid hormones assayed by ICMA,we aimed to evaluate the effect of obesity on the function of HPGA in prepubertal children;and to investigate the obesity rate of preschool children from 3 to 7 years old in Hudai and Mashan communities of Wuxi city.The obesity rates were compared according to four different criterions.Methods: The study was carried during May to December 2015.According to the Chinese Working Group on Obesity(WGOC)for Children 2010 revised BMI cut-offs,all children were divided into obesity,overweight,normal and lean groups respectively.To study the urine Gn and gonadal steroid hormones levels,first morning voided urine samples were collected.Urine luteinizing hormone(ULH),urine follicle stimulating hormone(UFSH)and urine gonadal steroid hormones(estriol,estradiol,testosterone and progesterone)were determined by ICMA.All the hormonal results were showed as median(25th-75 th percentiles),besides,timed urine hormones contents were calculated.Body mass index(BMI)and obese rate was compared by using the WGOC,the International Obesity Task Force(IOTF),the Centers for Disease Control(CDC)and the World Health Organization(WHO).Results: ⑴There were 1728 children(boys 936,girls 792)in this study.There were 125,90,628 and 90 cases in obese,overweight,normal and lean boys;and for girls they were 71,92,605 and 24 respectively.⑵ULH detectable rate(boys: 6.84%,girls: 15.66%)were lower than UFSH(boys: 99.47%,girls: 98.36%);that were also lower than urine gonadal steroid hormones(estriol,estradiol,testosterone and progesterone: 99.37%~99.97%).⑶The UFSH,UFSH contents and UFSH:Cr indexs of boys were all lower than those of girls(all P<0.05).⑷The UFSH contents,urine gonadal steroid hormones(estriol,estradiol and testosterone)contents in obese boys were respectively significant higher for the same indicator than overweight and normal boys(all P<0.05);however,there were no significant differences among obese,overweight and normal girls.⑸With the age growing,there was an increasing trend for UFSH contents among normal boys,and a declining trend among normal girls,while there was no significant trend among obese boys(or girls).⑹There was the highest obesity rate(11.34%)in WGOC standard,which were 3.16,1.78 and 2.58 times when compared to the IOTF(3.59%,P<0.001),CDC(6.37%,P<0.001)and WHO(4.40%,P<0.001)criterion respectively.⑺The boys’ obesity rate according to WGOC,IOTF,CDC and WHO criterions were all significantly higher than girls(13.35% vs 8.96%,P=0.005;5.13% vs 1.77%,P<0.001;9.29% vs 2.90%,P<0.001 and 7.16% vs 1.14%,P<0.001).Conclusion: ⑴Obesity could affect the function of HPGA in prepubertal children,especially for boys.⑵Because of the limit sensitivity of ULH assayed by ICMA in this study,UFSH could be more useful than ULH when used to evaluated the sexual development-related diseases.⑶According to the four standards of WGOC,IOTF,CDC and WHO,the obesity rate of prepubertal boys is higher than that of prepubertal girls,and there is the highest obesity rate for prepubertal children in WGOC standard.