Thienpont Linda M, Van Uytfanghe Katleen, Blincko Stuart, Ramsay Carol S, Xie Hui, Doss Robert C, Keevil Brian G, Owen Laura J, Rockwood Alan L, Kushnir Mark M, Chun Kelly Y, Chandler Donald W, Field Helen P, Sluss Patrick M
Laboratory for Analytical Chemistry, Faculty of Pharmaceutical Sciences, Gent University, Gent, Belgium.
Clin Chem. 2008 Aug;54(8):1290-7. doi: 10.1373/clinchem.2008.105841. Epub 2008 Jun 12.
The recent interest of clinical laboratories in developing serum testosterone assays based on isotope dilution-liquid chromatography-tandem mass spectrometry (ID-LC-MS/MS) stems from the lack of accuracy of direct immunoassays. In this study, we assessed the accuracy and state of standardization (traceability) of 4 published ID-LC-MS/MS procedures in a method comparison with an ID-gas chromatography (GC)-MS reference measurement procedure listed in the database of the Joint Committee for Traceability in Laboratory Medicine.
The study used 58 specimens from different patient categories. Each specimen was measured in triplicate (ID-LC-MS/MS) and quadruplicate (ID-GC-MS) in independent runs.
The testosterone concentrations by ID-GC-MS were 0.2-4.4 nmol/L (women), 0.2-2.0 nmol/L (hypogonadal man), and 10.1-31.3 nmol/L (normogonadal men). For ID-GC-MS, the CV was nearly constant, with a median of 1.0%; for ID-LC-MS/MS, it was concentration-dependent, with a median of up to 8%. Weighted Deming regression gave mean slopes, intercepts, and correlation coefficients of 0.90-1.11, -0.055-0.013 nmol/L, and 0.993-0.997, respectively. The % difference plot showed between 7% and 26% of the results outside a total error limit of 14%, with median deviations from ID-GC-MS between -9.6 and 0.4%.
This study demonstrated fairly good accuracy and standardization of the tested ID-LC-MS/MS procedures. Performance differences between procedures were evident in some instances, due to improper calibration and between-run calibration control. This emphasizes the need for thorough validation, including traceability, of new ID-LC-MS/MS procedures.
临床实验室最近对基于同位素稀释液相色谱-串联质谱法（ID-LC-MS/MS）开发血清睾酮检测方法产生兴趣，原因是直接免疫测定法缺乏准确性。在本研究中，我们通过与实验室医学溯源联合委员会数据库中列出的同位素稀释气相色谱（GC）-质谱参考测量程序进行方法比较，评估了4种已发表的ID-LC-MS/MS程序的准确性和标准化（溯源性）状态。
本研究使用了来自不同患者类别的58份标本。每个标本在独立运行中进行一式三份测量（ID-LC-MS/MS）和一式四份测量（ID-GC-MS）。
ID-GC-MS测定的睾酮浓度在女性中为0.2 - 4.4 nmol/L，性腺功能减退男性中为0.2 - 2.0 nmol/L，性腺功能正常男性中为10.1 - 31.3 nmol/L。对于ID-GC-MS，变异系数（CV）几乎恒定，中位数为1.0%；对于ID-LC-MS/MS，它与浓度相关，中位数高达8%。加权Deming回归得出的平均斜率、截距和相关系数分别为0.90 - 1.11、-0.055 - 0.013 nmol/L和0.993 - 0.997。%差异图显示，在14%的总误差限之外，7%至26%的结果与ID-GC-MS的中位数偏差在-9.6%至0.4%之间。
本研究表明，所测试的ID-LC-MS/MS程序具有相当好的准确性和标准化。由于校准不当和批间校准控制，某些情况下各程序之间的性能差异明显。这强调了对新的ID-LC-MS/MS程序进行全面验证（包括溯源性）的必要性。
