Shepherd J, Warner M H, Kilpatrick E S
Department of Clinical Biochemistry, Hull Royal Infirmary, Hull, UK.
Ann Clin Biochem. 2007 Jul;44(Pt 4):384-7. doi: 10.1258/000456307780945660.
The stability of creatinine in whole blood is unclear: it is not known if analysis of creatinine in samples with delayed separation could lead to misclassification of chronic kidney disease (CKD) using estimated glomerular filtration rate (eGFR).
Multiple blood samples were taken at a single time-point from five individuals and subject to varying time delays prior to centrifugation, after which serum was separated and analysed for creatinine by five different methods. The effect of time delay on eGFR was further investigated by measuring creatinine on duplicate patient samples arriving in the laboratory after immediate and delayed centrifugation.
A significant increase in creatinine was seen by 24 h using kinetic Jaffe methods (P<0.025). Over a period of 31 h creatinine concentration was stable using enzymatic creatinine assays. Using duplicate patient samples, four of 21 patients where specimens were delayed in the laboratory by more than 10 h showed a misclassification of CKD.
Delays in sample receipt can lead to significant increases in measured creatinine and misclassification of CKD. Enzymatic creatinine assays are reliable with respect to delayed sample receipt over the time course studied.
全血中肌酐的稳定性尚不清楚：对于延迟分离样本中的肌酐进行分析是否会导致使用估计肾小球滤过率（eGFR）对慢性肾脏病（CKD）进行错误分类尚不清楚。
在单个时间点从5名个体采集多个血样，并在离心前经历不同的时间延迟，之后分离血清并通过5种不同方法分析肌酐。通过对立即离心和延迟离心后到达实验室的患者重复样本测量肌酐，进一步研究时间延迟对eGFR的影响。
使用动力学碱性苦味酸法在24小时时可见肌酐显著增加（P<0.025）。在31小时内，使用酶法肌酐测定，肌酐浓度保持稳定。使用患者重复样本，21例样本在实验室延迟超过10小时的患者中有4例出现CKD错误分类。
样本接收延迟可导致测得的肌酐显著增加及CKD错误分类。在所研究的时间过程中，酶法肌酐测定对于延迟样本接收是可靠的。
