Variations in different thyroid stimulating hormone and free thyroxine detection kits for evaluating thyroid function during pregnancy / 中华围产医学杂志

ABSTRACT

Objective To assess the variations in different thyroid stimulating hormone(TSH) and free thyroxine (FT4) detection kits for evaluating thyroid function during pregnancy and to establish the corresponding normal reference ranges.Methods This study was based at the International Peace Maternity and Child Health Hospital affiliated to Shanghai Jiaotong University School of Medicine.A total of 200 pregnant women who visited the hospital between June,2011 and September,2012 were recruited in this study according to the National Academy of Clinical Biochemistry (NACB) criteria.Blood samples were sequentially collected from the women at the first (T1,9-12 weeks),second (T2,16-24 weeks) and third (T3,32-36 weeks) trimesters to determine the serum TSH and FT4 levels using four different detection kits (Siemens-C,Siemens-Ⅰ,Abott and Roche).A linear trend test was used to analyze serum TSH and FT4 levels with four different kits.A percentile range of P2.5 to P97.5 was used to establish the normal trimester-dependent reference ranges of TSH and FT4 levels for different detection kits.The Bootstrap method was used to compare the differences in the four reference ranges.Results Similar dynamic changes in TSH and FT4 levels during pregnancy were detected among the different kits (F=0.950,P=0.595; F=11.640,P=0.081,respectively).Among the four reference ranges of TSH,the Roche kit showed the most remarkable fluctuation during pregnancy,while Roche kit in the first trimester and Siemens C kit in the second and third trimesters showed larger fluctuations in reference ranges of FT4.More importantly,the reference ranges of TSH and FT4 showed significant variations among the four different kits in each trimester (TSHT1F=2 945.390,P ＜ 0.01; T2F=2 826.260,P ＜ 0.01; T3F=1 698.360,P ＜ 0.01.FT4TlF=1 145.440,P ＜ 0.01; T2F=2 260.240,P ＜ 0.01; T3F=1 439.920,P ＜ 0.01).Conclusions TSH and FT4 measurement using four different commercial kits showed similar trimester-dependent dynamic changes.However,it is necessary to establish trimester-dependent and detection kit dependent normal reference ranges of TSH and FT4 for thyroid function evaluation for pregnant women.