Sakai Hiroyuki, Fukuda Gen, Suzuki Naoko, Watanabe Choji, Odawara Masato
Division of Diabetology, Metabolism and Endocrinology, The Third Department of Internal Medicine, Tokyo Medical University, Tokyo, Japan.
Endocr J. 2009;56(3):435-40. doi: 10.1507/endocrj.k08e-361. Epub 2009 Apr 1.
We encountered a 60-year-old woman with remarkably elevated thyroid-stimulating hormone (TSH) level as measured by electrochemiluminescent immunoassay (ECLIA), but with no specific symptoms, and with normal levels of free T3 and free T4. We performed the following investigations: polyethylene glycol (PEG) precipitation test, human antimouse IgG antibody (HAMA) interference test, and 3 additional TSH measurements by chemiluminescent immunoassay (CLIA). We then performed 2 gel filtration chromatography (GFC) procedures; one was at pH 7.2, and the other was at pH 3.0. Although the recovery of TSH shown by the PEG precipitation test was 4% which was extremely low, no HAMA interference was observed. Moreover, 3 CLIA instruments also showed various high values. The first GFC showed that the main peak of TSH immunoreactivity by ECLIA was located at a slightly larger molecular weight position than that of IgG. By the second GFC, the sample from the peak fraction of the first GFC showed that the TSH peak disappeared completely at the previous retention time but newly appeared at the same retention time as the TSH monomer. Protein G-Agarose gel removed the majority of the TSH complex. In conclusion, the majority of TSH in her serum was macro-TSH; TSH and anti- TSH IgG autoantibody complex. We should keep the possibility of macro-TSH in mind in cases with unexpectedly high TSH values, especially in autoimmune thyroidal disorders.
我们遇到一名60岁女性，通过电化学发光免疫分析（ECLIA）测得其促甲状腺激素（TSH）水平显著升高，但无特定症状，且游离T3和游离T4水平正常。我们进行了以下检查：聚乙二醇（PEG）沉淀试验、人抗小鼠IgG抗体（HAMA）干扰试验，以及另外3次通过化学发光免疫分析（CLIA）测量TSH。然后我们进行了2次凝胶过滤色谱（GFC）操作；一次在pH 7.2下进行，另一次在pH 3.0下进行。尽管PEG沉淀试验显示TSH的回收率为4%，极低，但未观察到HAMA干扰。此外，3台CLIA仪器也显示出各种高值。第一次GFC显示，ECLIA检测到的TSH免疫反应性主峰位于比IgG分子量稍大的位置。通过第二次GFC，来自第一次GFC峰馏分的样品显示，TSH峰在之前的保留时间完全消失，但在与TSH单体相同的保留时间重新出现。蛋白G-琼脂糖凝胶去除了大部分TSH复合物。总之，她血清中的大部分TSH是大分子TSH；即TSH与抗TSH IgG自身抗体复合物。在TSH值意外升高的情况下，尤其是在自身免疫性甲状腺疾病中，我们应考虑到大分子TSH的可能性。
