Bayer M F, McDougall I R
Clin Chim Acta. 1982 Feb 5;118(2-3):209-18. doi: 10.1016/0009-8981(82)90008-0.
During severe systemic illness total thyroid hormone levels are often low, and measurement of total hormones often does not differentiate between euthyroid and hypothyroid patients. Therefore, we examined serum free thyroxine levels by radioimmunoassay (antibody-coated tubes, Clinical Assays) as an alternative diagnostic test in three groups of severely ill patients with subnormal triiodothyronine. Free thyroxine estimates agreed with the clinical impression and TSH in 91% of cases in group 1 (47 patients with no history or clinical evidence of thyroid disorder), in 96% of cases in group 2 (24 euthyroid patients with a previous history of thyroid disease, including some on thyroid replacement) and 90% of cases in group 3 (10 hypothyroid patients). By contrast, the free thyroxine index did so in only 53% (group 1), 46% (group 2) or 100% (group 3). Sequential studies showed little change in free thyroxine and TSH levels in euthyroid patients during illness and recovery, and a good negative correlation between free thyroxine and TSH in hypothyroid patients. Free thyroxine measurements (and TSH) discriminate between euthyroid and hypothyroid sick patients better than other thyroid function tests including the free thyroxine index, and can be employed routinely: a distinct advantage over free thyroxine measured by equilibrium dialysis.
在严重的全身性疾病期间，总甲状腺激素水平常常较低，而且总激素的测定往往无法区分甲状腺功能正常和甲状腺功能减退的患者。因此，我们采用放射免疫分析法（抗体包被管，临床检测法）检测了三组三碘甲状腺原氨酸水平低于正常的重症患者的血清游离甲状腺素水平，作为一种替代诊断测试。在第1组（47例无甲状腺疾病病史或临床证据的患者）中，91%的病例游离甲状腺素估计值与临床印象及促甲状腺激素（TSH）相符；在第2组（24例有甲状腺疾病既往史的甲状腺功能正常患者，包括一些正在接受甲状腺替代治疗的患者）中，96%的病例相符；在第3组（10例甲状腺功能减退患者）中，90%的病例相符。相比之下，游离甲状腺素指数在第1组（53%）、第2组（46%）或第3组（100%）中与临床印象及TSH相符的比例仅为上述水平。连续研究表明，甲状腺功能正常的患者在患病和康复期间游离甲状腺素和TSH水平变化不大，而甲状腺功能减退患者的游离甲状腺素与TSH之间存在良好的负相关。游离甲状腺素测量值（及TSH）在区分甲状腺功能正常和甲状腺功能减退的患病患者方面比包括游离甲状腺素指数在内的其他甲状腺功能测试更好，并且可以常规使用：这是相对于通过平衡透析法测定游离甲状腺素的一个明显优势。
