The Study On Thyroid Function Tests Index During Pregnancy

Objectives: This study attempts to survey the thyroid hormone and thyroidantibody level of pregnant women in the antenatal examination from ourhospital and to explore the prevalence and changes of thyroid functionof pregnant women and to put forward the suggestions on the pregnancythyroid function screening.Methods: This study conducts a Cross-sectional study on289cases ofpregnant women from the maternity clinic in the First Affiliated Hospitalof Fujian Medical University, starting from September2011to November2011. A prevalence comparison is made on the high-risk pregnant women andall pregnant women of the antenatal examination, on the thyroid peroxidaseantibodies (TPOAb) positive women and TPOAb negative women. This paperalso makes a correlation analysis on the thyroid-stimulating hormone(TSH), TPOAb and serum free thyroxine (FT4) and explores the gestationage-specific reference intervals for thyroid hormones under the normallevel of iodine intake and analyzes its rationality. The SPSS18.0systemis used to analyze the statistics data. The skewed distribution data areexpressed with median. Comparison between non-normal distribution datais made using rank sum test. Numeration data is compared using thechi-square test and fisher ’ s precise test. Correlation analysis is madethrough Spearman rank correlation test, while Multi-factor variable isanalyzed by multiple regression analysis.. A‘P’value of less than0.05is considered to be statistically significant.Results:1.For the pregnant women,the prevalence of hyperthyroidism, subclinicalhyperthyroidism, hypothyroidism, subclinical hypothyroidism，isolatedmaternal hypothyroxinemia and TPOAb positivity is1.44%,6.73%,6.25%, 10.58%,9.62%,13.6%,respectively.A case-finding strategy for screeningthyroid function in the high-risk group would miss about72.2%pregnantwomen with thyroid disorders.2.TSH is related positively with TPOAb and negatively with FT4.Antibodypositivity is a risk factor for the elevation of serum TSH level.FT4andthe pregnancy trimester are protective factors for the elevation of serumTSH level.3.During the second trimester of pregnancy, the prevalence of subclinicalhypothyroidism is significantly higher in TPOAb-positive women ascompared with TPOAb-negative women. The level of serum TSH issignificantly higher in TPOAb-positive women as compared withTPOAb-negative women.4. During pregnancy periods, serum free three iodine armour gland originalacid (FT3), serum FT4and serum TSH of normal pregnant women areconsistently lower than non-pregnant levels. The FT3level and the FT4level Continues to decline. The down trend remains stable in the secondand the third trimester. Serum TSH of normal pregnant women is at a lowlevel in the first trimester and is elevated in the second trimester, thendecreases slightly in the third trimester.Conclusions: This study indicates a higher prevalence of thyroid diseasein selected pregnant women and the universal thyroid function screeningfor the pregnant women has its rationality. The serum thyroid hormonevalues should be obtained early in pregnancy. Serum TSH is the mostaccurate indication of thyroid status in pregnancy than any of thesealternative methods. And it is necessary to assess serum FT4. TPOAb isrelated positively with TSH and a risk factor for the elevation of serumTSH level. There is no evidence that the incidence of thyroid diseasesis higher in subjects with positive thyroid antibodies. Screening allwomen for anti-thyroid antibodies in pregnancy is not recommended. Serum thyroid hormone values of normal pregnant women are consistently lowerthan non-pregnant levels. It is suggested that establishing thepregnancy-specific thyroid screening criteria under the local normallevel of iodine intake.