National Center for Clinical Laboratories, Institute of Geriatric Medicine, Chinese Academy of Medical Sciences, Beijing Hospital/National Center of Gerontology, PR China; Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, PR China.
National Center for Clinical Laboratories, Institute of Geriatric Medicine, Chinese Academy of Medical Sciences, Beijing Hospital/National Center of Gerontology, PR China.
Clin Chim Acta. 2025 Jan 15;565:119944. doi: 10.1016/j.cca.2024.119944. Epub 2024 Sep 6.
Free thyroid hormone (FTH) serves as the preferred indicator for the clinical assessment of thyroid function, mainly encompassing free thyroxine and free triiodothyronine. The immunoassay commonly employed in the clinical setting exhibits certain unresolvable deficiencies. The results of over 5,500 clinical laboratories for FTH from China in 2024 demonstrated that the outcomes of immunoassay were not comparable, with robust CVs calculated in accordance with ISO 13528 ranging from 13.82% to 21.42%. Establishing reference methods is an important tool to achieve accurate and comparable results of free hormones. Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) holds a distinct advantage in the precise detection of small molecules, and two reference methods for free thyroxine based on LC-MS/MS are included in the JCTLM list. This article conducts a comprehensive review of the detection methods and standardization of FTH. It presents the metabolism of thyroid hormones, the significance of detection, the techniques, and application examples of free thyroid hormone assays, and deliberates on the current status, prospects, and recommendations for the standardization of FTH assays. Immunoassay and LC-MS/MS, as significant techniques for FTH detection, are predominantly emphasized in the case references. Ultrafiltration and equilibrium dialysis, which are utilized to separate FTH, are also addressed. This article aims to discuss the status quo of FTH detection and clarify the advantages of LC-MS/MS in FTH detection, propose that LC-MS/MS can be utilized as an auxiliary validation method or alternative method in clinical applications, and offer suggestions for the standardization of testing results.
游离甲状腺激素（FTH）是评估甲状腺功能的首选指标，主要包括游离甲状腺素和游离三碘甲状腺原氨酸。临床常用的免疫分析法存在一些无法解决的缺陷。2024 年，中国 5500 多家临床实验室的 FTH 检测结果表明，免疫分析法的结果不可比，按照 ISO 13528 计算的稳健变异系数范围为 13.82%至 21.42%。建立参考方法是实现游离激素准确可比结果的重要工具。液相色谱-串联质谱法（LC-MS/MS）在小分子的精确检测方面具有明显优势，JCTLM 列表中包含两种基于 LC-MS/MS 的游离甲状腺素参考方法。本文全面回顾了 FTH 的检测方法和标准化。介绍了甲状腺激素的代谢、检测的意义、游离甲状腺激素检测技术和应用实例，并讨论了 FTH 检测的现状、前景和标准化建议。免疫分析法和 LC-MS/MS 是 FTH 检测的主要技术，在案例研究中得到了重点强调。还讨论了用于分离 FTH 的超滤和平衡透析技术。本文旨在讨论 FTH 检测的现状，阐明 LC-MS/MS 在 FTH 检测中的优势，提出 LC-MS/MS 可在临床应用中作为辅助验证方法或替代方法，并就检测结果的标准化提出建议。
