Hasselström K, Siersbaek-Nielsen K, Lumholtz I B, Faber J, Kirkegaard C, Friis T
Acta Endocrinol (Copenh). 1985 Dec;110(4):483-6. doi: 10.1530/acta.0.1100483.
A new method for the estimation of the bioavailability of thyroxine (T4) and 3,5,3'-triiodothyronine (T3) is described based on gel separation followed by antibody extraction of labelled T4 and T3 from serum, and using the area under the curve of disappearance of the tracer (AUC) for the calculations. The peak serum concentrations of radioactive labelled T4 and T3 were reached approximately 90 min after oral administration of both tracers. The relative difference of duplicate estimations was below 10% (n = 3). The bioavailability of T4 in 6 euthyroid controls was in median 65% (range 64-75%), and it was significantly increased both in hyperthyroidism (88% (75-99%), n = 6, P less than 0.01) and hypothyroidism (84% (67-100%), n = 6, P less than 0.02). The bioavailability of T3 in 6 euthyroid controls was in median 78% (69-99%) and significantly greater than that of T4 (P less than 0.02). The bioavailability was unaffected by hyperthyroidism (79% (61-98%), n = 9) and hypothyroidism (77% (66-97%), n = 7). No significant difference between T4 and T3 bioavailabilities was found in hyper- or hypothyroidism. The clinical implication of the present study is that the bioavailability of T4 and T3 is almost identical and approximately 80% in patients with severe hypothyroidism.
本文描述了一种估算甲状腺素（T4）和3,5,3'-三碘甲状腺原氨酸（T3）生物利用度的新方法，该方法基于凝胶分离，随后从血清中提取标记的T4和T3抗体，并使用示踪剂消失曲线下的面积（AUC）进行计算。口服两种示踪剂后，放射性标记的T4和T3血清峰值浓度在约90分钟后达到。重复估算的相对差异低于10%（n = 3）。6名甲状腺功能正常对照者中T4的生物利用度中位数为65%（范围64 - 75%），在甲状腺功能亢进症（88%（75 - 99%），n = 6，P < 0.01）和甲状腺功能减退症（84%（67 - 100%），n = 6，P < 0.02）中均显著增加。6名甲状腺功能正常对照者中T3的生物利用度中位数为78%（69 - 99%），显著高于T4（P < 0.02）。生物利用度不受甲状腺功能亢进症（79%（61 - 98%），n = 9）和甲状腺功能减退症（77%（66 - 97%），n = 7）的影响。在甲状腺功能亢进或减退症中，未发现T4和T3生物利用度之间存在显著差异。本研究的临床意义在于，在严重甲状腺功能减退症患者中，T4和T3的生物利用度几乎相同，约为80%。
