Piketty M L, Bounaud M P, Bounaud J Y, Lebtahi R, Valat C, Askienazy S, Begon F, Besnard J C
Laboratoire de Radioimmunologie, Centre Hospitalier Sainte Anne, Paris, France.
Eur J Clin Chem Clin Biochem. 1992 Aug;30(8):485-92.
The two-step enzymatic immunoassay of free thyroxine (IMx FT4, Abbott Laboratories, Chicago, IL) was studied in three centres. The assay involved a fluorimetric measurement and took 45 minutes using a completely automated procedure. The results were compared with those from the free thyroxine two-step radioimmunoassay and with the "calculation" of free thyroxine. The analytical precision was found to be excellent if the analyser was correctly set. The IMx FT4 assay seemed unaffected by increased concentrations of albumin and of non-esterified fatty acids (oleic acid) up to 5 mmol/l. The euthyroid reference interval, defined as that including 95% of 194 control subjects, was 12-21 pmol/l. A limited overlap existed between euthyroid and hyperthyroid patients, but a larger one was seen between the euthyroid and hypothyroid population, the latter including subclinical hypothyroidism. IMx FT4 results agreed well when compared with those from two-step radioimmunoassays. The IMx FT4 technique gave rise to a low percentage of elevated results in patients being treated with heparin, but was undisturbed by autoantibodies to thyroxine and triiodothyronine which were present in one hypothyroid patient.
在三个中心对游离甲状腺素的两步酶免疫测定法（IMx FT4，雅培实验室，伊利诺伊州芝加哥）进行了研究。该测定涉及荧光测量，采用完全自动化程序需时45分钟。将结果与游离甲状腺素两步放射免疫测定法的结果以及游离甲状腺素的“计算值”进行了比较。如果分析仪设置正确，分析精密度极佳。IMx FT4测定法似乎不受白蛋白和非酯化脂肪酸（油酸）浓度高达5 mmol/L时升高的影响。正常甲状腺功能参考区间定义为包括194名对照受试者中95%的范围，为12 - 21 pmol/L。正常甲状腺功能患者与甲状腺功能亢进患者之间存在有限的重叠，但在正常甲状腺功能患者与甲状腺功能减退人群（包括亚临床甲状腺功能减退）之间重叠更大。与两步放射免疫测定法的结果相比，IMx FT4结果吻合良好。在接受肝素治疗的患者中，IMx FT4技术导致结果升高的比例较低，但不受一名甲状腺功能减退患者体内存在的甲状腺素和三碘甲状腺原氨酸自身抗体的干扰。
