Hamada S, Kosaka T, Torizuka K
Clin Chim Acta. 1975 Sep 1;63(2):129-37. doi: 10.1016/0009-8981(75)90155-2.
A rapid and simple method is described for the indirect measurement of free thyroxine (T4) concentration and maximal thyroxine-binding globulin (TBG) capacity applying a single kit of Thyopac-4. Initially, a value for total T4 is determined, after which the patient's serum is added to permit estimation of T4 corrected for abnormal TBG concentration. The ratio of increased radioactivity in the supernatant after the addition of patient's serum to that obtained using pooled normal serum is designated the TBG index, being directly related to the amount of TBG in the added serum. The index is significantly increased in hypothyroidism and pregnancy, and decreased in hyperthyroidism, correlating well with the TBG capacity measured by reverse-flow paper electrophoresis. A free T4 index (FTI) can be calculated from the values for T4 and TBG index, because the TBG index is reciprocally related to the serum uptake test (T3-resin). Values for FTI are significantly increased and decreased in hyper- and hypothyroidism, respectively, whereas they remain within the normal range in pregnancy and TBG deficiency. The FTI is shown to bear a nearly straight-line relationship to that calculated from separate estimations of T4 and the serum uptake test (T3-resin).
本文描述了一种使用单一试剂盒Thyopac - 4间接测量游离甲状腺素（T4）浓度和最大甲状腺素结合球蛋白（TBG）容量的快速简便方法。首先测定总T4值，然后加入患者血清以估计针对异常TBG浓度校正后的T4。加入患者血清后上清液中放射性增加量与使用混合正常血清获得的放射性增加量之比称为TBG指数，它与加入血清中TBG的量直接相关。该指数在甲状腺功能减退症和妊娠时显著升高，在甲状腺功能亢进症时降低，与逆流纸电泳测量的TBG容量相关性良好。游离T4指数（FTI）可根据T4和TBG指数值计算得出，因为TBG指数与血清摄取试验（T3 - 树脂）呈反比关系。FTI值在甲状腺功能亢进症和甲状腺功能减退症时分别显著升高和降低，而在妊娠和TBG缺乏时保持在正常范围内。结果表明，FTI与通过分别测定T4和血清摄取试验（T3 - 树脂）计算得出的值呈近似直线关系。
