Müller-Brand J, Fridrich R, Staub J J
Nuklearmedizin. 1982 Oct;21(5):169-73.
The evaluation of "preclinical hyperthyroidism" includes laboratory and in vivo tests. The measurements of circulating total thyroxine (T4) and total triiodothyronine (T3) depend on the plasma concentration of thyroid hormone binding proteins. A simple approach, the calculation of the free T3 index (FT3I) and the augmented FT3I (aFT3I) from total T3 and T3-resin uptake corrects the total serum T3 for variation in thyroid hormone binding capacity. In a group of 95 patients with border-line elevated T3 levels we have correlated the results of FT3I and aFT3I with clinical, biochemical and radioisotope findings. It was shown that in patients with moderate elevation of T3 the FT3I and aFT3I are capable of distinguishing clearly between the euthyroid and hyperthyroid range. To detect an imbalance in the hypothalamic-pituitary-thyroid axis either the T4-suppression test or the TRH-test could be used. In 60 patients with "preclinical hyperthyroidism" we have compared both of them. In 77% of the patients the T4-suppression test and i.v. TRH-test provided concomitant results. In 13 patients without response to the i.v. TRH-test 7 showed a definite (more than 50%) and 6 a partial suppression (10-40%) of radioiodine uptake. This suggests that there is no sharp distinction between hyper- and euthyroidism.
“临床前甲状腺功能亢进症”的评估包括实验室检查和体内试验。循环总甲状腺素（T4）和总三碘甲状腺原氨酸（T3）的测量取决于甲状腺激素结合蛋白的血浆浓度。一种简单的方法，即根据总T3和T3树脂摄取量计算游离T3指数（FT3I）和增强游离T3指数（aFT3I），可校正血清总T3中甲状腺激素结合能力的变化。在一组95例T3水平临界升高的患者中，我们将FT3I和aFT3I的结果与临床、生化及放射性核素检查结果进行了关联分析。结果显示，在T3中度升高的患者中，FT3I和aFT3I能够清晰地区分正常甲状腺功能和甲状腺功能亢进状态。为检测下丘脑 - 垂体 - 甲状腺轴的失衡，可采用T4抑制试验或促甲状腺激素释放激素（TRH）试验。在60例“临床前甲状腺功能亢进症”患者中，我们对这两种试验进行了比较。77%的患者T4抑制试验和静脉注射TRH试验结果一致。在13例对静脉注射TRH试验无反应的患者中，7例显示放射性碘摄取有明确抑制（超过50%），6例有部分抑制（10 - 40%）。这表明甲状腺功能亢进和正常甲状腺功能之间没有明显界限。
