| Objective:The aim of the present study was to acquaint the iodine nutrition status and its influence factors of pregnant women,and to establish a suitable reference intervals of serum free thyroid hormone(FT4),free three triiodothyronine(FT3),thyroid stimulating hormone(TSH)of childbearing-age women in Chengde area.Methods:(1)Pregnant women who visited the outpatient or inpatient department of Affilicated Hospital of Chengde Medical University between October 2015 and May 2016 were selected continuously as object of this study.Inclusion criteria:(1)Living in Chengde for more than 2 years;(2)Aged 20~40 years;(3)Pregnant women are single pregnancy;(4)A day without eating high iodine food or taking drugs containing iodine before collecting urine.Exclusion criteria:(1)Women with thyroid disease;(2)Women who suffered from other autoimmune diseases;(3)Women with hyperemesis gravidarum or pregnancy complication or severe medical or surgical diseases;(4)Women who have a special diet or bad habits(drug,smoking,alcohol).We finally recruited 443 pregnant women,using arsenic cerium catalytic assay method for quantitative detection of their urine iodine levels,and recorded their age,gestational age,residence and tastes.(2)478 pregnant women and 122 nonpregnant women who visited the outpatient or inpatient department of Affilicated Hospital of Chengde Medical University between October 2015 and May 2016 were selected continuously as pregnant group and control group.Inclusion criteria:(1)Living in Chengde for more than 2 years;(2)Aged 20~40 years;(3)Pregnant women are singlepregnancy.Exclusion criteria:(1)Positive thyroid peroxidase antibody(TPOAb);(2)Positive thyroglobulin antibody(TGAb);(3)Women who suffered from other autoimmune diseases;(4)Women who took the drugs which can effect thyroid function except estrogen;(5)Women with hyperemesis gravidarum or pregnancy complication or severe medical or surgical diseases.Using electrochemiluminescence immunoassay to detect the FT4,FT3,TSH,TPOAb and TGAb of pregnant women and non pregnant women.Using SPSS 19.0 software to establish a database for statistical analysis of the data,we use the median(four percentile,four quantile)[M(P25~P75)] to describe the age,gestational age,urine iodine and thyroid function indexes,comparison between groups using two independent samples Wilcoxon test,Kruskal-Wallis H test and multiple comparisons Nemenyi test;iodine deficiency rate were compared with Chi-aquare test,the difference was statistically significant when P<0.05;the multiple comparisons of iodine deficiency rate take P<0.0125 as difference was statistically significant.The bilateral 95% reference intervals(P2.5~P97.5)of thyroid function indexes was establishend by percentile method.Results:(1)The urine iodine of 443 pregnant women ranges from 41.2g/L to928.8g/L,the median is 190.10g/L,women whose urine iodine less than 150g/L accounted for 34.1%,whose urine iodine less than 100g/L accounted for12.4%,whose urine iodine less than 50g/L accounted for 0.5%.The amount of iodine beyond appropriate amount(250g/L?urine iodine<500g/L)accounted for 24.4%,the amount of iodine excess(urine iodine?500g/L)accounted for6.1%.The difference of urine iodine level in different gestation(H=0.618,P=0.734),age(Z=0.096,P=0.923),residence(Z=0.609,P=0.543),taste(Z=1.704,P=0.088)of pregnant women were not statistically significant.There was no significant difference in iodine deficiency rate among pregnant women in different gestation(X2=3.415,P=0.181),age(X2=2.461,P=0.117)and residence(X2=0352,P=0.553).There was significant difference in iodine deficiency rate among pregnant women with different dietary taste(X2=4.496,P=0.034).The difference of the iodine excess rate between different gestation was statistically significant(X2=9.17,P=0.01),pairwise comparison shows that the early and late gestational period(X2=6.949,P=0.008)had significant difference,the early and mid gestational period(X2=4.538,P=0.033)and the mid and late gestational period(X2=0.851,P=0.356)both had no significant difference;iodine excess rate of pregnant women in different age(X2=3.388,P=0.066),residence(X2=0.042,P=0.838),and dietary taste(X2=2.369,P=0.124)were no statistically significant.(2)The reference intervals of thyroid function indexs of pregnant women:FT4:12.77~25.12pmol/L in early pregnancy,10.94~19.13pmol/L in mid pregnancy,and 8.54~14.62pmol/L in late pregnancy;FT3:4.02~6.07pmol/L in early pregnancy,3.48~5.79pmol/L in mid pregnancy,and3.18~5.09pmol/L in late pregnancy;TSH:0.02~3.69 m IU/L in early pregnancy,0.03~6.70 m IU/L in mid pregnancy,and 0.45~6.02 m IU/L in late pregnancy.Nonpregnant women: FT4:11.46~20.07pmol/L;FT3:3.65~6.26pmol/L;TSH:0.08~4.75 m IU/L.There were significant differences in FT4(H=290.015,P<0.05),FT3(H=181.332,P<0.05),TSH(H=110.261,P<0.05)between pregnant women in different gestation and nonpregnant women.Using this newly-established reference intervals to evaluate the pregnant women in this study,the detection rates of subclinical hypothyroidism,clinical hypothyroidism,subclinical hyperthyroidism,clinical hyperthyroidism and simple hypothyroxinaemia(10th)were 1.88%,0.42%,1.46%,0.63% and9.62%.Conclusions:With the decrease of salt iodine concentration,the iodine nutrition level of pregnant women in Chengde area was suitable.The pregnant women with mild taste were more likely to have iodine deficiency.Iodine excess mostly occurs in early pregnancy women.Compared the gestational age-specific reference intervals for maternal thyroid function in Chengde area established in this study with the recommended intervals for Chinese women in "Guidelines for diagnosis and treatment of pregnancy and postpartum thyroid diseases " which put out in 2012,the range of FT4 is quite similar,the range of TSH in early pregnancy have some difference.The newly established reference intervals reduces the rate of missed diagnosis of subclinical hypothyroidism of pregnant women,and also reduces the misdiagnosis rate of subclinical hyperthyroidism of pregnant women in Chengde. |
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