Introduction

Immunoassays and liquid chromatography-tandem mass spectrometry assays are commonly employed in clinical laboratories for measurement of total testosterone in serum. Results obtained from either of these methodologies compare poorly due to differences in calibration and/or inadvertent detection of interfering substances by the immunoassays. Standardization efforts are underway, but recent studies indicate that accuracy remains an issue.

Methods

This study compares the results from four independently developed and validated LC-MS/MS assays for total testosterone. The calibration for each assay was verified using National Institute of Standards and Technology Standard Reference Material 971.

Results

Initially, one of the four assays had a mean percent difference of +11.44%, compared to the All Method Mean, but following re-verification of all five non-zero calibrator concentrations with the NIST SRM 971, the mean percent difference decreased to −4.88%. Subsequently, the agreement between all four assays showed a mean bias of <5% across the range of all testosterone concentrations (0.13–38.10 nmol/L; 3.7–1098 ng/dL), including at low concentrations of <1 nmol/L (<29 ng/dL).

Conclusions

Excellent agreement between four independently developed LC-MS/MS assays demonstrates that harmonization using standard reference material is attainable. However, as we found in this study, to ensure accurate calibration it is critical to validate the concentrations of new lots of calibrators.

中文翻译：

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四种经过临床验证的睾酮 LC-MS/MS 检测方法的比较：协调一致是一个可以实现的目标

介绍

免疫测定和液相色谱-串联质谱测定通常在临床实验室中用于测量血清中的总睾酮。由于校准的差异和/或免疫测定对干扰物质的无意检测，从这两种方法中获得的结果比较差。标准化工作正在进行中，但最近的研究表明准确性仍然是一个问题。

方法

本研究比较了四种独立开发和验证的 LC-MS/MS 总睾酮测定的结果。使用美国国家标准与技术研究院标准参考材料 971 验证每个测定的校准。

结果

最初，与所有方法平均值相比，四种测定中的一种的平均百分比差异为 +11.44%，但在使用 NIST SRM 971 重新验证所有五种非零校准物浓度后，平均百分比差异降至 - 4.88%。随后，所有四种测定之间的一致性显示在所有睾酮浓度范围内（0.13-38.10 nmol/L；3.7-1098 ng/dL）的平均偏差<5%，包括在<1 nmol/L的低浓度下。 <29 纳克/分升）。

结论

四种独立开发的 LC-MS/MS 分析之间的出色一致性表明，使用标准参考材料可以实现协调一致。然而，正如我们在本研究中发现的那样，为确保准确校准，验证新批次校准物的浓度至关重要。