Russell N J, Foster S, Clark P, Robertson I D, Lewis D, Irwin P J
School of Veterinary & Biomedical Sciences, Division of Veterinary Clinical Science, Murdoch University, WA 6150, Australia.
Aust Vet J. 2007 Dec;85(12):487-94. doi: 10.1111/j.1751-0813.2007.00232.x.
Non-radioactive assay methods are widely used in commercial laboratories to measure canine blood cortisol concentrations, despite a paucity of published validity data of these tests compared with the traditional 'gold standard' radioimmunoassay.
To compare a commercial chemiluminescence assay with radioimmunoassay for blood cortisol measurement, determine the effect of storage on the radioimmunoassay, and determine the impact of any differences on clinical decisions.
The study included 54 client owned dogs undergoing adrenal function testing. Fresh plasma or serum samples (n=170) were assayed for cortisol using radioimmunoassay (RIA1). Samples (n=196) were also frozen and stored in batches, and assayed by chemiluminescence and radioimmunoassay (RIA2).
Overall, there was a strong correlation (r2=0.967, P<0.001) between RIA2 and chemiluminescence concentrations without significant difference between means. Strong correlations were present for RIA2 and chemiluminescence at concentration subgroups of >400 nmol/L (r2=0.869, P<0.001), <100 nmol/L (r2=0.790, P<0.001), and <40 nmol/L (r2=0.738, P<0.001). Significant differences between means were present for RIA2 and chemiluminescence concentrations in the <100 nmol/L, and <40 nmol/L (P<0.001) groups. Despite a significant difference in RIA1 and RIA2 results overall, there was no significant difference between RIA1 and RIA2 for any of the concentration groups. In seven cases, discrepant RIA2 and chemiluminescence results may have altered clinical decisions.
Although RIA and chemiluminescence cortisol concentrations appear highly correlated, a significant difference may exist for concentrations less than 100 nmol/L in stored canine sera. Results of chemiluminescence cortisol assays should be interpreted with caution unless the specific assay method in the laboratory has been adequately validated in dogs.
尽管与传统的“金标准”放射免疫分析法相比，这些检测方法的有效性数据公布较少，但非放射性检测方法仍在商业实验室中广泛用于测量犬类血液皮质醇浓度。
比较一种商业化学发光分析法与放射免疫分析法在血液皮质醇测量中的差异，确定储存对放射免疫分析法的影响，并确定任何差异对临床决策的影响。
该研究纳入了54只接受肾上腺功能检测的客户拥有的犬只。使用放射免疫分析法（RIA1）对新鲜血浆或血清样本（n=170）进行皮质醇检测。样本（n=196）也被冷冻并分批储存，然后通过化学发光法和放射免疫分析法（RIA2）进行检测。
总体而言，RIA2与化学发光法检测的皮质醇浓度之间存在强相关性（r2=0.967，P<0.001），均值之间无显著差异。在皮质醇浓度>400 nmol/L（r2=0.869，P<0.001）、<100 nmol/L（r2=0.790，P<0.001）和<40 nmol/L（r2=0.738，P<0.001）的亚组中，RIA2与化学发光法之间也存在强相关性。在<100 nmol/L和<40 nmol/L（P<0.001）组中，RIA2与化学发光法检测的皮质醇浓度均值存在显著差异。尽管RIA1和RIA2的总体结果存在显著差异，但在任何浓度组中，RIA1和RIA2之间均无显著差异。在7例病例中，RIA2与化学发光法的结果差异可能改变了临床决策。
尽管放射免疫分析法和化学发光法检测的皮质醇浓度似乎高度相关，但在储存的犬血清中，浓度低于100 nmol/L时可能存在显著差异。除非实验室中的特定检测方法已在犬类中得到充分验证，否则化学发光法检测皮质醇的结果应谨慎解释。
