Maberly G, Waite K, Ma G, Soni N, Eastman C
Clin Chem. 1986 Apr;32(4):616-20.
Serum from normal, pregnant, and severely ill patients was stripped of endogenous thyroid hormones and diluted 1100-fold in barbital buffer. We then used it to study the binding characteristics of thyroxin binding globulin (TBG), noting significant differences in binding capacities among the groups. The mean (+/- SD) triiodothyronine/thyroxin ratio for binding capacity was 18 +/- 4 for normal subjects. The ratio was significantly increased in pregnant patients, 21 +/- 4 (p less than 0.05), and significantly lower in severely ill patients, 12 +/- 4 (p less than 0.05). When serum was diluted before assay, to give a uniform TBG concentration among groups, these apparent differences in binding characteristics were eliminated. It therefore is unlikely that different molecular species of TBG account for the variations in binding characteristics in these clinical states. Apparently, the distribution of thyroxin and triiodothyronine among the binding sites on TBG changes with variations in TBG concentration. This may explain the discrepancies observed in the concentrations of free thyroid hormones as estimated by various methodologies.
将正常、怀孕和重症患者的血清去除内源性甲状腺激素，并在巴比妥缓冲液中稀释1100倍。然后我们用它来研究甲状腺素结合球蛋白（TBG）的结合特性，注意到各组之间的结合能力存在显著差异。正常受试者结合能力的平均（±标准差）三碘甲状腺原氨酸/甲状腺素比值为18±4。怀孕患者的该比值显著升高，为21±4（p<0.05），而重症患者的该比值显著降低，为12±4（p<0.05）。当在测定前对血清进行稀释，以使各组之间的TBG浓度一致时，这些结合特性的明显差异就消除了。因此，不同分子形式的TBG不太可能是这些临床状态下结合特性变化的原因。显然，甲状腺素和三碘甲状腺原氨酸在TBG结合位点之间的分布会随着TBG浓度的变化而改变。这可能解释了通过各种方法估计的游离甲状腺激素浓度中观察到的差异。
