"Unbound analog" radioimmunoassays for free thyroxin measure the albumin-bound hormone fraction.
"Unbound analog" radioimmunoassays for free thyroxin measure the albumin-bound hormone fraction.
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游离甲状腺素的“未结合类似物”放射免疫测定可测量白蛋白结合激素部分。
作者：
Jan R. Stocklgt;V. Stevens;E. L. White;J. Barlow
我们评估了白蛋白结合甲状腺素（T4）对两种“未结合类似物”游离T4方法（AmerlexR游离T4和Clinical Assays一步游离T4）获得的表观游离T4值的影响。我们评估了三种不同白蛋白异常的血清：完全遗传性无白蛋白血症、部分纠正的无白蛋白血症和家族性异常白蛋白血症性高甲状腺素血症，其中异常白蛋白结合类似物示踪剂与高表观游离T4值相关。在遗传性无白蛋白血症，游离T4是几乎检测不到的两种检测，相反，游离T4平衡透析是正常的。加入游离T4人血清白蛋白后，总遗传性无白蛋白血症的表观游离T4浓度通过模拟方法变得正常。在未经治疗的遗传性总白蛋白缺乏症中，[125 I]T4和未鉴定的标记试剂盒类似物通过抗人白蛋白血清的免疫沉淀可以忽略不计，在家族性白蛋白异常性高甲状腺素血症中约为正常值的两倍。因此，示踪剂与白蛋白结合的改变与通过模拟方法获得的表观游离T4浓度相关。未鉴定的类似物示踪剂和T4与白蛋白的相互作用使得这些技术主要反映白蛋白结合的T4部分。
We have assessed the influence of albumin-bound thyroxin (T4) on apparent free T4 values obtained by two "unbound analog" free T4 methods (AmerlexR Free T4 and Clinical Assays one-step Free T4). We evaluated sera showing three different albumin anomalies: total hereditary analbuminemia, partially corrected analbuminemia, and familial dysalbuminemic hyperthyroxinemia, where abnormal albumin-binding of analog tracer is associated with high apparent free T4 values by these methods. In hereditary analbuminemia, free T4 was almost undetectable by both assays; in contrast, free T4 by equilibrium dialysis was normal. After addition of T4-free human serum albumin, the apparent free T4 concentration in total hereditary analbuminemia became normal by the analog methods. Immunoprecipitation of [125I]T4 and the unidentified labeled kit analogs by antiserum to human albumin was negligible in untreated total hereditary analbuminemia and approximately twice normal in familial dysalbuminemic hyperthyroxinemia. Therefore, alterations in tracer binding to albumin correlate with the apparent free T4 concentrations obtained by the analog methods. The interactions of the unidentified analog tracers and T4 with albumin are such that these techniques principally reflect the albumin-bound T4 moiety.