Korte Wolfgang, Engler Hanna, Riesen Walter F, Brinkmann Thomas
Institut für Klinische Chemie und Hämatologie, Kantonsspital St. Gallen, St. Gallen, Switzerland.
Clin Lab. 2012;58(7-8):645-57.
Different FT3 and FT4 assays report significantly different results. We compared the distribution of FT3 and FT4 in a cohort of Swiss patients measured with DxI 800, AxSYM, and Immulite 2000.
TSH, FT3, and FT4 values were measured in 1,938 serum samples. Patients were classified on the basis of their TSH values as low, normal, and high. For each class of TSH values, concordances of FT3 and FT4 results were determined among the three assays.
For low TSH values in all three assays FT3 (FT4) concordance of DxI - AxSYM, DxI--Immulite, and AxSYM--Immulite was determined as 83.1%, 76.2% 68.5% (60.8%, 74.6%, 83.1%), for normal TSH as 89.2%, 79.0%, 75.3% (83.9%, 85.5%, 83.1%) and for elevated TSH as 78.0%, 86.0%, 78.0% (84.0%, 90.0%, 90.0%), respectively. Low FT4 concordance rates with DxI 800 were mainly caused by its FT4 upper reference limit of 14.1 pmol/L. Using a cut-off of 16.1 pmol/L concordances with AxSYM and Immulite were improved to 77.7% and 86.9% (low TSH), 92.5% and 96.2% (normal TSH), and 90.0% and 92.2% (high TSH). Low FT3 concordance rates with Immulite were caused by its low FT3 upper reference limit of 6.29 pmol/L as 11.6% of patient samples with normal TSH value showed unusually elevated FT3 results.
We showed an overall good concordance of FT3 and FT4 results, when stratified according to corresponding TSH values and the appropriate reference range is used. However, our data also show that problems of interpretation of results based on numerical values have yet not been solved.
不同的游离三碘甲状腺原氨酸（FT3）和游离甲状腺素（FT4）检测方法报告的结果存在显著差异。我们比较了在一组瑞士患者中使用DxI 800、AxSYM和Immulite 2000检测的FT3和FT4的分布情况。
检测了1938份血清样本中的促甲状腺激素（TSH）、FT3和FT4值。根据患者的TSH值将其分为低、正常和高三类。对于每一类TSH值，确定三种检测方法之间FT3和FT4结果的一致性。
对于所有三种检测方法中的低TSH值，DxI - AxSYM、DxI - Immulite和AxSYM - Immulite之间FT3（FT4）的一致性分别确定为83.1%、76.2%、68.5%（60.8%、74.6%、83.1%）；对于正常TSH值，一致性分别为89.2%、79.0%、75.3%（83.9%、85.5%、83.1%）；对于升高的TSH值，一致性分别为78.0%、86.0%、78.0%（84.0%、90.0%、90.0%）。DxI 800的低FT4一致性率主要是由于其FT4参考上限为14.1 pmol/L。使用16.1 pmol/L的临界值，与AxSYM和Immulite的一致性分别提高到77.7%和86.9%（低TSH）、92.5%和96.2%（正常TSH）以及90.0%和92.2%（高TSH）。与Immulite的低FT3一致性率是由于其FT3参考上限低至6.29 pmol/L，因为11.6%的TSH值正常的患者样本显示FT3结果异常升高。
当根据相应的TSH值进行分层并使用适当的参考范围时，我们发现FT3和FT4结果总体上具有良好的一致性。然而，我们的数据也表明，基于数值的结果解释问题尚未得到解决。
