Kunst A, Seidenschwarz E, Bürk H, Schauer S, Haug H, Lehmann P, Ehrhardt V
Boehringer Mannheim GmbH, Biochemical Research Centre, Tutzing, F.R.G.
Clin Chem. 1988 Sep;34(9):1830-3.
This enzyme immunoassay for free thyroxin (FT4) involves simultaneous incubation of sample and thyroxin conjugated to horseradish peroxidase (EC 1.11.1.7) in antibody-coated tubes at room temperature. The test can be performed in 90 min. It is not influenced by variations in concentrations of thyroxin-binding globulin (TBG), thyroxin-binding prealbumin, or albumin. With increased concentrations of non-esterified fatty acids, the measured FT4 equivalent concentrations increase immediately, indicating displacement of endogenous thyroxin from its binding sites. FT4 values obtained with this assay for 110 samples, including sera with low albumin and high TBG as well as sera of patients treated with heparin, agreed well with those measured by a two-step radioimmunoassay and with the T4/TBG ratio. The measurable range of FT4 with our assay is 2.5 to 65 ng/L. Intra-assay CVs range from 3.4% to 2.2%, interassay CVs from 6.6% to 2.6% at concentrations of 9 to 45 ng of FT4 equivalent per liter.
这种游离甲状腺素（FT4）酶免疫测定法是在室温下，将样品与结合辣根过氧化物酶（EC 1.11.1.7）的甲状腺素同时在抗体包被管中孵育。该检测可在90分钟内完成。它不受甲状腺素结合球蛋白（TBG）、甲状腺素结合前白蛋白或白蛋白浓度变化的影响。随着非酯化脂肪酸浓度的增加，测得的FT4等效浓度立即增加，表明内源性甲状腺素从其结合位点被置换出来。用该检测方法对110份样品（包括低白蛋白和高TBG血清以及肝素治疗患者的血清）测得的FT4值，与两步放射免疫测定法测得的值以及T4/TBG比值吻合良好。我们的检测方法可测FT4范围为2.5至65 ng/L。在每升9至45 ng FT4等效物浓度下，批内变异系数范围为3.4%至2.2%，批间变异系数范围为6.6%至2.6%。
