Sakata S, Komaki T, Ogawa T, Takuno H, Matsui I, Sarui H, Kojima N, Takamatsu J, Miura K
Third Department of Internal Medicine, Gifu University School of Medicine, Japan.
Clin Chim Acta. 1993 Oct 15;219(1-2):23-34. doi: 10.1016/0009-8981(93)90194-9.
Serum free thyroxine (FT4) levels were measured in patients with Hashimoto's thyroiditis and Graves' disease who were seropositive for thyroid hormone autoantibodies. The methods used were equilibrium dialysis/radioimmunoassay (FT4 by equilibrium dialysis, Nichols Institute) and FT4 analog radioimmunoassay (Amerlex MFT4) before and after treatment of sera with 12.5% polyethylene glycol (PEG). Furthermore, FT4 measurement in the PEG-treated sera was done using two other analog radioimmunoassays (DPC FT4 Kit and N-FT4 Corning). Serum thyrotropin (TSH) concentration before and after i.v. infusion of thyrotropin releasing hormone (TRH) was measured in five cases of Hashimoto's thyroiditis and four cases of Graves' disease with thyroid hormone autoantibodies. Although FT4 determination by analog tracer radioimmunoassays showed unusually high values for the hormone, results obtained by an equilibrium dialysis/radioimmunoassay method showed compatible values with basal TSH. Furthermore, FT4 concentrations measured with Amerlex MFT4 after treatment of sera with 12.5% PEG, correlated well with the values obtained by equilibrium dialysis/radioimmunoassay (r = 0.98, P < 0.001). Similar results were obtained with two other analog FT4 radioimmunoassays after treatment of sera with PEG. These results indicate that real FT4 values in patients with thyroid hormone autoantibodies are compatible with basal TSH concentrations. The presence of thyroid hormone autoantibodies per se does not affect the control mechanism of the hypothalamo-pituitary-thyroid axis. It was concluded that measurement of basal TSH as well as FT4 values by either equilibrium dialysis/radioimmunoassay or analog radioimmunoassays after PEG treatment provides clinicians with valid information for assessment of the precise status of thyroid function in patients with thyroid hormone autoantibodies.
对甲状腺激素自身抗体血清学阳性的桥本甲状腺炎和格雷夫斯病患者测定血清游离甲状腺素（FT4）水平。所采用的方法为平衡透析/放射免疫分析法（通过平衡透析测定FT4，尼科尔斯研究所）以及在血清用12.5%聚乙二醇（PEG）处理前后的FT4类似物放射免疫分析法（Amerlex MFT4）。此外，使用另外两种类似物放射免疫分析法（DPC FT4试剂盒和康宁N-FT4）对经PEG处理的血清进行FT4测定。对5例桥本甲状腺炎和4例伴有甲状腺激素自身抗体的格雷夫斯病患者静脉输注促甲状腺激素释放激素（TRH）前后的血清促甲状腺激素（TSH）浓度进行了测定。尽管通过类似物示踪放射免疫分析法测定FT4显示该激素的值异常高，但通过平衡透析/放射免疫分析方法获得的结果与基础TSH值相符。此外，血清用12.5% PEG处理后通过Amerlex MFT4测定的FT4浓度与通过平衡透析/放射免疫分析法获得的值相关性良好（r = 0.98，P < 0.001）。血清用PEG处理后，另外两种类似物FT4放射免疫分析法也得到了类似结果。这些结果表明，甲状腺激素自身抗体患者的实际FT4值与基础TSH浓度相符。甲状腺激素自身抗体的存在本身并不影响下丘脑 - 垂体 - 甲状腺轴的调控机制。得出的结论是，通过平衡透析/放射免疫分析法或PEG处理后的类似物放射免疫分析法测定基础TSH以及FT4值，可为临床医生提供有效信息，以评估甲状腺激素自身抗体患者甲状腺功能的精确状态。
