Université Catholique de Louvain, Cliniques Universitaires Saint-Luc, Brussels, Belgium.
Clin Chem Lab Med. 2011 Dec;49(12):1987-99. doi: 10.1515/CCLM.2011.674. Epub 2011 Jul 29.
Serum creatinine is important for detecting the beginning of a decline in kidney function. The Beckman Coulter Jaffe reagents for measuring creatinine have been standardized to the internationally accepted reference method: isotope dilution mass spectrometry (IDMS). The impact of this recalibration on the Beckman Coulter modular or cup (stat) Jaffe method is studied.
Recalibrated Jaffe (calibrator set points IDMS traceable) and classic National Institute of Standards and Technology (NIST) creatinine methods (traceable to NIST 914a) were compared with an enzymatic method (Sentinel, traceable to NIST SRM 967). All measurements were performed on Synchron DxC 800 systems. Imprecision of the routine methods was studied using the Clinical and Laboratory Standards Institute (CLSI) protocols and laboratory quality survey. Thirteen plasma pools, with concentrations < 354 mmol/L, were analyzed with a gas chromatography isotope dilution mass spectrometry (GC-IDMS) method and routine methods. Total error of 8.2% based on biological variability, set on the GC-IDMS values and acceptance criteria (bias < 5%, imprecision < 8% at concentrations ≥ 88.4 mmol/L and a maximum 10% increase in the relative error of estimated glomerular filtration rate (eGFR) of the National Kidney Disease Educational Program (NKDEP) were used for evaluating analytical performance of the routine methods studied.
After recalibration of the Jaffe method, median bias (mmol/L) decreased from 12.4 (95% CI: 9.1-21.2) to 7.3 (95% CI: 1.5-10.5). Imprecision of the Jaffe method is in agreement with the claim of the manufacturer, namely < 9 mmol/L or < 3% below or above 292 mmol/L. Below creatinine of 88.4 mmol/L, imprecision of the recalibrated Jaffe and enzymatic methods is between 4.1% and 6.9%, and 5.0% and 7.1%, respectively, and significantly different (p = 0.02 for both the Jaffe and enzymatic methods) from the goal, based on biological variability, of 2.7%. For the adult pools, all recalibrated Jaffe and enzymatic results fall within the total error of 8.2%. In the pediatric samples, one-third of the recalibrated Jaffe and three of the six enzymatic results fall within this total error goal.
Recalibration significantly reduced bias of the Jaffe method. For pediatric samples, recalibrated Jaffe results do not comply with either the imprecision goal or the total error based on biological variability. Adult recalibrated Jaffe results are in compliance with the goals based on biological variability and with the acceptance criteria from the NKDEP.
血清肌酐对于检测肾功能下降的开始非常重要。用于测量肌酐的贝克曼库尔特 Jaffe 试剂已经标准化为国际公认的参考方法：同位素稀释质谱法（IDMS）。本研究旨在研究这种重新校准对贝克曼库尔特模块或杯（stat）Jaffe 方法的影响。
比较了重新校准的 Jaffe（校准器设定点可溯源至 IDMS）和经典的美国国家标准与技术研究院（NIST）肌酐方法（可溯源至 NIST 914a）与酶法（Sentinel，可溯源至 NIST SRM 967）。所有测量均在 Synchron DxC 800 系统上进行。使用临床和实验室标准协会（CLSI）方案和实验室质量调查研究常规方法的精密度。使用气相色谱同位素稀释质谱法（GC-IDMS）方法和常规方法分析了浓度<354mmol/L 的 13 个血浆池。基于生物变异性设定的 8.2%总误差（基于 GC-IDMS 值和接受标准（偏差<5%，在浓度≥88.4mmol/L 时精度<8%，以及国家肾脏疾病教育计划（NKDEP）估计肾小球滤过率（eGFR）的相对误差最大增加 10%）用于评估所研究常规方法的分析性能。
Jaffe 方法重新校准后，中位数偏差（mmol/L）从 12.4（95%CI：9.1-21.2）降至 7.3（95%CI：1.5-10.5）。Jaffe 方法的精密度符合制造商的要求，即<9mmol/L 或<292mmol/L 时低于或高于 3%。在肌酐<88.4mmol/L 时，重新校准的 Jaffe 和酶法的精密度分别为 4.1%-6.9%和 5.0%-7.1%，与基于生物变异性的 2.7%的目标显著不同（Jaffe 和酶法的 p 值均为 0.02）。对于成人样本，所有重新校准的 Jaffe 和酶法结果均在 8.2%总误差范围内。在儿科样本中，三分之一的重新校准 Jaffe 和六分之一的酶法结果符合该总误差目标。
重新校准显著降低了 Jaffe 方法的偏差。对于儿科样本，重新校准的 Jaffe 结果既不符合精密度目标，也不符合基于生物变异性的总误差目标。成人重新校准的 Jaffe 结果符合基于生物变异性的目标，也符合 NKDEP 的接受标准。
