Ponder Michelle, Lamos Elizabeth, Munir Kashif
University of Maryland Medical Center, 22 S Green St., RM N3E09, Baltimore, MD 21201-1554, USA.
Division of Endocrinology, Diabetes, and Nutrition, University of Maryland School of Medicine, 827 Linden Avenue, 2nd Floor, Baltimore, MD 21201, USA.
Case Rep Endocrinol. 2021 Nov 17;2021:1152572. doi: 10.1155/2021/1152572. eCollection 2021.
Thyroglobulin (Tg) monitoring is the biochemical standard for surveillance of recurrent differentiated thyroid cancer (DTC). Several assays are available to quantify Tg levels: immunometric assay (IMA), radioimmunoassay (RIA), and the newer liquid chromatography tandem mass spectrometry (LC-MS). It is well known that a number of entities can interfere with the accuracy of testing, and at this point in time, no one assay perfectly balances high sensitivity with low risk of interference. In this case study, we present two cases in which treatment with desiccated thyroid extract (Armour thyroid) led to a sudden elevation in Tg, which resolved when Armour thyroid was discontinued. This elevation occurred when Tg was measured with both IMA and LC-MS, which suggests direct interference from porcine Tg rather than heterophilic or thyroglobulin antibody (TgAb) interference. We suggest that patients with a history of DTC not be treated with desiccated thyroid extracts consistent with guidelines. Furthermore, more advances need to be made in the area of Tg testing to improve specificity and avoid detection of nonhuman Tg and other similar proteins.
甲状腺球蛋白（Tg）监测是复发性分化型甲状腺癌（DTC）监测的生化标准。有几种检测方法可用于量化Tg水平：免疫测定法（IMA）、放射免疫测定法（RIA）以及更新的液相色谱串联质谱法（LC-MS）。众所周知，许多因素会干扰检测的准确性，目前，没有一种检测方法能完美地平衡高灵敏度和低干扰风险。在本病例研究中，我们展示了两例使用干燥甲状腺提取物（Armour甲状腺）治疗导致Tg突然升高的病例，停用Armour甲状腺后Tg升高情况得到缓解。当使用IMA和LC-MS检测Tg时均出现了这种升高，这表明是猪Tg的直接干扰，而非嗜异性或甲状腺球蛋白抗体（TgAb）干扰。我们建议，有DTC病史的患者不应按照指南使用干燥甲状腺提取物进行治疗。此外，在Tg检测领域还需要取得更多进展，以提高特异性并避免检测到非人类Tg和其他类似蛋白质。
