Witherspoon L R, el Shami A S, Shuler S E, Neely H, Sonnemaker R, Gilbert S S, Alyea K
Department of Nuclear Medicine, Ochsner Clinic, New Orleans, LA 70121.
Clin Chem. 1988 Jan;34(1):17-23.
Chemical blockers used to displace thyronine analog from albumin in analog kits for assay of free thyroxin (FT4) or free triiodothyronine (FT3) may also displace thyroxin (T4) or triiodothyronine (T3) from thyroxin-binding globulin (TBG), resulting in an apparent TBG dependence of results of free hormone estimates. We used equilibrium dialysis and antibody binding to assess the displacement of thyronine analogs and thyronines from albumin and TBG by use of chemical blockers. We chose a combination of two chemical blockers, which eliminated thyronine analog-albumin binding but minimized thyronine displacement from TBG for use in FT4 and FT3 assays. These blocked-analog free-hormone assays yielded accurate clinical results in euthyroid patients, hypo- and hyperthyroid patients, and in pregnant women. FT4 results were not entirely normalized in all nonthyroidally ill patients, indicating that decreased analog-albumin binding is not the only factor resulting in low FT4 results. In current Diagnostic Products Corp. (DPC) FT4 and FT3 blocked-analog kits, the blocker concentrations are the same as we used in these assays.
用于在游离甲状腺素（FT4）或游离三碘甲状腺原氨酸（FT3）检测试剂盒中从白蛋白上置换甲状腺素类似物的化学阻断剂，也可能从甲状腺素结合球蛋白（TBG）上置换甲状腺素（T4）或三碘甲状腺原氨酸（T3），导致游离激素估计结果明显依赖于TBG。我们使用平衡透析和抗体结合来评估化学阻断剂对甲状腺素类似物和甲状腺素从白蛋白和TBG上的置换情况。我们选择了两种化学阻断剂的组合，该组合消除了甲状腺素类似物与白蛋白的结合，但将甲状腺素从TBG上的置换降至最低，用于FT4和FT3检测。这些阻断类似物的游离激素检测在甲状腺功能正常的患者、甲状腺功能减退和亢进的患者以及孕妇中都产生了准确的临床结果。在所有非甲状腺疾病患者中，FT4结果并未完全恢复正常，这表明类似物与白蛋白结合的减少并非导致FT4结果偏低的唯一因素。在当前诊断产品公司（DPC）的FT4和FT3阻断类似物试剂盒中，阻断剂浓度与我们在这些检测中使用的相同。
