Pandian M R, Morgan C, Nelson J C, Fisher D A
Nichols Institute, San Juan Capistrano, CA 92675.
Clin Chem. 1990 Mar;36(3):457-61.
Using the simple method of protein analysis described here, we could identify thyroxin (T4)-binding-protein abnormalities in euthyroid patients with hyperthyroxinemia or hypothyroxinemia. Serum incubated with [125I]thyroxin was analyzed by agarose gel electrophoresis, with bromphenol blue staining of protein. The relative distribution of radioactive T4 was determined for each binding protein--thyroxin-binding globulin (TBG), transthyretin, albumin, and T4-binding immunoglobulin (when present)--and the mass of T4 bound to each was determined. We also used sensitive immunoassays to quantify TBG, transthyretin, and albumin concentrations, then calculated the mass of T4 (as determined by electrophoresis) bound per unit mass of the respective binding protein. When the concentration of binding proteins was altered (e.g., TBG excess or TBG deficiency), the T4 binding/mass ratio for each protein remained within the expected range; but when the functional affinity of a binding protein was altered--as in dysalbuminemic hyperthyroxinemia and in low-T4 nonthyroidal illness--this ratio was abnormal. This procedure can be used to help identify TBG excess, TBG deficiency, dysalbuminemic hyperthyroxinemia, prealbumin-associated hyperthyroxinemia, variant TBG with reduced affinity for T4, euthyroid sickness, and T4-binding autoantibodies.
使用本文所述的简单蛋白质分析方法，我们能够在甲状腺功能正常但甲状腺素血症或甲状腺素减少血症的患者中识别甲状腺素（T4）结合蛋白异常。将血清与[125I]甲状腺素一起孵育，通过琼脂糖凝胶电泳进行分析，并用溴酚蓝对蛋白质进行染色。确定每种结合蛋白（甲状腺素结合球蛋白（TBG）、转甲状腺素蛋白、白蛋白和T4结合免疫球蛋白（如果存在））的放射性T4相对分布，并确定与每种蛋白结合的T4质量。我们还使用灵敏的免疫测定法来定量TBG、转甲状腺素蛋白和白蛋白浓度，然后计算每单位质量相应结合蛋白结合的T4质量（通过电泳确定）。当结合蛋白浓度改变时（例如，TBG过量或TBG缺乏），每种蛋白的T4结合/质量比仍在预期范围内；但当结合蛋白的功能亲和力改变时，如在异常白蛋白血症性甲状腺素血症和低T4非甲状腺疾病中，该比值则异常。此程序可用于帮助识别TBG过量、TBG缺乏、异常白蛋白血症性甲状腺素血症、前白蛋白相关性甲状腺素血症、对T4亲和力降低的变异TBG、甲状腺功能正常疾病和T4结合自身抗体。
