The Normal Reference Range Of Thyroid Function In Pregnant Women In Xi'an City

Objectives: Women of childbearing age are at high risk of thyroid diseases.Thyroid dysfunction not only increases the risk of many pregnancy-related diseases,but also leads to a variety of adverse pregnancy outcomes.With the increase of the understanding of thyroid disease during pregnancy.“Guidelines for diagnosis and treatment of thyroid disorders during pregnancy and postpartum”,published jointly by ATA,Europe thyroid association,the American college of obstetricians and gynecologists,iodine global network society and maternal-fetal medicine,in 2017,recommend to establish different people in different normal reference range of thyroid function during pregnancy.In China's guidelines for diagnosis and treatment of thyroid diseases in pregnancy and postpartum,it is also recommended to establish the reference value of specific thyroid indexes in the local area or unit.Although the normal reference range of pregnancy specific thyroid function has been preliminarily discussed in xi 'an city,it has not been widely promoted due to single reagent or poor stability of reagent.Therefore,this study aims to establish the normal reference range of female specific thyroid function during pregnancy in xi 'an city and to understand the changes of thyroid hormone during pregnancy.Methods: According to the recommendations of the National Academy of Sciences Clinical Biochemical Research Institute(NACB),a total of 597 pregnant women were collected at the Department of Obstetrics and Gynecology in Xi'an Central Hospital from December 2017 to July 2018,including Pregnant women undergoing routine check-ups and normal women of childbearing age who are examined before pregnancy.536 women in pregnancy were experimental group and divided into three groups according to gestational age: 194 in early pregnancy(gestational weeks ?12+6 weeks,T1 phase),212 in the second trimester(13-27+6 weeks,T2 phase).130 in the third trimester(28 to 40 weeks,T3 phase),61 normal women of childbearing age as a control group.General data collection from all included populations,and morning fasting blood was taken to measure TSH,FT3,FT4,TPOA,Tg Ab,liver and kidney function,and fasting venous blood glucose.All data collected was entered into the EXCEL form and analyzed using SPSS19.0.First,the data was tested for normality,obeying the normal distribution data,using ±s and comparing between two groups and multiple groups using two independent sample t-test and one-way ANOVA.The data that did not obey the normal distribution were described by the median and percentile method.The reference value range was 95%confidence interval(P2.5~P97.5).The comparison between the two groups and the comparison between groups were performed by rank sum test.(Mann-Whitney U,Kruskal-Wallis H),P < 0.05 indicates that the difference was statistically significant.Results:1.The ages of the experimental group and the control group all obeyed the normal distribution,There was no significant difference between the experimental group and the control group.There was no significant difference in the ages of T1,T2 and T3.P>0.05.2.The FT3 of the experimental group and the control group all obeyed the normal distribution.The normal reference range of FT3 in the control group and the experimental group were: 3.44~6.78 pmol/l,T1 phase 3.77~6.55 pmol/l,T2 phase 3.41~6.11 pmol/l,T3 phase 3.32 ~ 5.16 pmol / l.With the increase of gestational age during pregnancy,FT3 showed a gradual decline trend,and there were statistical differences in FT3 during pregnancy,P <0.05.3.The FT4 of the experimental group and the control group did not obey the normal distribution.The normal reference range of FT4 in control group and T1,T2 and T3 phases were 12.82~22.72 pmol/l and 12.59~21.59 pmol/l,11.09 ~ 21.11 pmol/l,10.78 ~17.58 pmol/l respectively.FT4 gradually decreased with gestational age after pregnancy,and the difference between each pregnancy was statistically significant,P <0.05.4.The TSH of the control group and the experimental group did not obey thenormal distribution.The normal reference range of TSH in the control group and T1,T2 and T3 phases were 0.77 ~ 4.92 u IU/ml and 0.12 ~ 4.15 u IU/ml,0.29~4.20 u IU/ml,0.76~4.23 u IU/ml respectively.After pregnancy,TSH was depressed significantly,and the whole pregnancy was lower than the control group,but gradually increased with the increase of gestational age.There were statistical differences between the experimental group and the control group,P<0.05.Conciusions:1.In this study,the reference range of female specific thyroid hormone during pregnancy in xi 'an city was established.2.Thyroid hormone levels in pregnant women were different from those in non-pregnant women,and there were changes between different pregnancies.