The Circulating Levels Of NtproCNP In Girls With Idiopathic Central Precocious Puberty

Objective: To assess the relationship between the bone development biomarker NTproCNP and development in adolescent,through evaluating the circulation levels of IGF-1, E₂ and NT-proCNP in healthy girls and idiopathic central precocious puberty girls.Methods: A total of 16 cases of girls with ICPP were set as ICPP group,while the control group involed 16 of healthy girls with age matched. Physical detection indices such as height,weight were determined and bone age were measured by evaluating ossificative index at hand and wrist by CHN method. Blood sa--m ples (4-5ml)were withdrawn from selected fasting children at 8-10a.m. Bl-ood for NT-proCNP measurement was collected into chilled tubes containing EDTA,centifuged at 4。C.Blood samples for determing E2 was collected into tubers without anticoagulant and centifuged for 5 min.Both the plasma and se-rum were stored at -80。C untill analysis. NT-proCNP in plasma and IGF-1in serum were measured by enzyme linked immunosorbent assay (ELISA) ,while the serum estrogen was measured by chemiluminescent method. All of deter-mining processes were accomplished in one time. All statictical analysis was preceded by the application of SPSS 13.0 statistic software.Means±SD(x±s) and median(inter-quartile range)(M(Q)) was respectively used to depict the measurement data with normal distribution and skewed distribution.The plasma NT-proCNP values in ICPP group and serum estrogen levels in healthy group are not normally distributed,so the comparisons of NT-proCNP and estrogen between two groups were analysed by ANOVA.Pearson's correlation coefficient was used to test the assosiation between two variables with a normal distribution,and Spearman's correlation was used in case of a skewed dsitribution.The significance level was set at P≦ 0.05. Results:1 The comparison of physical indexes between ICPP girls and healthy girlsThe chronological age,bone age and height age in health gilrs were respectively 8.5±1.8,8.3±2.0 and 7.8±1.7,there was no diference between them(F=0.69,P=0.51);while in ICPP group were respectively 8.2±1.5,11.2(1.5)and 10.5(2.5) , bone age was much advanced in ICPP group(λ2=20.728,p<0.001).There was no differece of chronological age between health girls and ICPP girls(t=0.994,P>0.05),while the bone age was significantly advancede in ICPP girls(z=-3.247 , P<0.05).The breast development was assessed by Turner scales:in health group 11 children in Turnerâ… ,3 children in Turnerâ…¡,2 children in Turnerâ…¢and no children in Turnerâ…£and Turnerâ…¤;in ICPP group:4 children in Turnerâ…¡,6 children in Turnerâ…¢,6 children in Turnerâ…£.2 The comparision of NTproCNP,IGF-1 and estrogen The concentrations of estrogen in health group and ICPP group were respectively 37.19±16.08pg/ml and 19.00(4.5)pg/ml, and there existed significant difference(z=2.58,P<0.05).The plasma levels of NTproCNP in health group and ICPP group were respectively 21.74(13.12)pmol/ml and 18.92±8.62pmol/ml。The concentrations of IGF-1 in health group and ICPP group were respectively 867.50±318.15ng/ml and522.41±228.33ng/ml, and there existed significant difference(t=3.59,P<0.05).3 The correlation between serum estrogen,IGF-1,NTproCNP and age,bone ageIn healthy group,there was positive correlation between serume IGF-I and age,bone age;while we did not found the relationship between plasma NTproCNP and age,bone age.In ICPP group and all subujects,we did not find any relationship between them.Conclusions: 1 In puberty,the elevation of the NTproCNP levels in circulation may be regulated by estrogen.2 As IGF-I ,NT-proCNP may also take part in regulating the puberty growth spurt.