In routine clinical laboratories, serum creatinine is typically measured on automated analyzers using colorimetric or enzymatic assays, which are both susceptible to interferences that can lead to incorrect measurement. Here, we present a straightforward and rapid LC-MS/MS assay for serum creatinine using methanol extraction, with separation performed using a strong cation exchange column. Results from this newly developed method were compared against those from an automated Abbott Architect kinetic Jaffe method. We also assessed the effect of bilirubin and glucose, as interferants, on both methods.

Our LC-MS/MS assay has a run time of 1.1 min, uses a relatively small sample volume of 10 µL and has a within-batch imprecision of 1.1–1.8% at the concentrations tested, which is within the range necessary for routine clinical use. Recovery from serum samples spiked with creatinine was >95%, and glucose and bilirubin were not found to interfere in the assay. Glucose was observed to significantly interfere in the kinetic Jaffe method, while bilirubin had a variable effect. We also determined that creatinine can be measured from saliva using our method, and that salivary concentrations are, on average, 15% of those in serum. This assay provides an alternative for patient sample analysis where interference is expected in routine creatinine methods.

在常规临床实验室中，血清肌酐通常在自动分析仪上使用比色法或酶法进行测量，这两种方法都容易受到干扰，导致测量不正确。在这里，我们提出了一种使用甲醇提取的血清肌酐的直接且快速的 LC-MS/MS 检测方法，并使用强阳离子交换柱进行分离。将这种新开发方法的结果与自动 Abbott Architect 动力学 Jaffe 方法的结果进行比较。我们还评估了胆红素和葡萄糖作为干扰物对这两种方法的影响。

我们的 LC-MS/MS 分析的运行时间为 1.1 分钟，使用相对较小的 10 µL 样品体积，并且在测试浓度下的批内不精确度为 1.1-1.8%，这在常规临床试验所需的范围内用。加标肌酐的血清样品的回收率 > 95%，未发现葡萄糖和胆红素干扰测定。观察到葡萄糖显着干扰动态 Jaffe 方法，而胆红素具有可变影响。我们还确定可以使用我们的方法从唾液中测量肌酐，并且唾液浓度平均为血清中浓度的 15%。该测定为患者样本分析提供了一种替代方法，其中预期在常规肌酐方法中存在干扰。