背景:准确可靠地检测人血清游离甲状腺素(FT4)对于甲状腺疾病的诊断和治疗至关重要。然而,人们对FT4测量在患者护理中的表现提出了担忧。疾病控制和预防中心临床标准化计划(CDC-CSP)通过创建FT4标准化计划来标准化FT4测量来解决这些问题。该研究旨在开发一种高度准确和精确的候选参考测量程序(cRMP),作为CDC-CSP的一个关键组成部分,用于FT4测量的标准化。
方法:根据临床和实验室标准研究所C45-A指南和已发布的RMP[23]中的推荐条件,采用平衡透析(ED)将血清FT4与蛋白质结合的甲状腺素分离。用液相色谱-串联质谱法(LC-MS/MS)直接定量透析液中的FT4,无需衍生。试样和校准溶液的重量测量,校准器括号,同位素稀释,增强的色谱分辨率,和T4特定的质量转变用于确保准确性,精度,和cRMP的特异性。
结果:在实验室间比较研究中,所述cRMP与已建立的RMP和其他两种cRMP非常吻合。每种方法对总体实验室平均值的平均偏差在±2.5%内。日内,跨日,cRMP的总不精确性在4.4%以内。检出限为0.90pmol/L,对于甲状腺功能减退症患者的FT4具有足够的敏感性。透析液中T4和内源性组分的结构类似物不干扰测量。
结论:我们的ED-LC-MS/MScRMP提供了很高的准确性,精度,特异性,和灵敏度的FT4测量。cRMP可以作为建立测量可追溯性的高级标准,并为FT4测定的标准化提供准确性基础。
BACKGROUND: Accurate and reliable measurement of human serum free thyroxine (FT4) is critical for the diagnosis and treatment of thyroid diseases. However, concerns have been raised regarding the performance of FT4 measurements in patient care. Centers for Disease Control and Prevention Clinical Standardization Programs (CDC-CSP) address these concerns by creating a FT4 standardization program to standardize FT4 measurements. The study aims to develop a highly accurate and precise candidate Reference Measurement Procedure (cRMP), as one key component of CDC-CSP, for standardization of FT4 measurements.
METHODS: Serum FT4 was separated from protein-bound thyroxine with equilibrium dialysis (ED) following the recommended conditions in the Clinical and Laboratory Standards Institute C45-A guideline and the published RMP [20,21,23]. FT4 in dialysate was directly quantified with liquid chromatography-tandem mass spectrometry (LC-MS/MS) without derivatization. Gravimetric measurements of specimens and calibrator solutions, calibrator bracketing, isotope dilution, enhanced chromatographic resolution, and T4 specific mass transitions were used to ensure the accuracy, precision, and specificity of the cRMP.
RESULTS: The described cRMP agreed well with the established RMP and two other cRMPs in an interlaboratory comparison study. The mean biases of each method to the overall laboratory mean were within ±2.5%. The intra-day, inter-day, and total imprecision for the cRMP were within 4.4%. The limit of detection was 0.90 pmol/L, which was sufficiently sensitive to determine FT4 for patients with hypothyroidism. The structural analogs of T4 and endogenous components in dialysate did not interfere with the measurements.
CONCLUSIONS: Our ED-LC-MS/MS cRMP provides high accuracy, precision, specificity, and sensitivity for FT4 measurement. The cRMP can serve as a higher-order standard for establishing measurement traceability and provide an accuracy base for the standardization of FT4 assays.