Voskoboev Nikolay V, Cambern Sarah J, Hanley Matthew M, Giesen Callen D, Schilling Jason J, Jannetto Paul J, Lieske John C, Block Darci R
Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA.
Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA; Department of Internal Medicine, Mayo Clinic, Rochester, MN, USA.
Clin Biochem. 2015 Nov;48(16-17):1126-30. doi: 10.1016/j.clinbiochem.2015.06.011. Epub 2015 Jun 17.
Validation of tests performed on body fluids other than blood or urine can be challenging due to the lack of a reference method to confirm accuracy. The aim of this study was to evaluate alternate assessments of accuracy that laboratories can rely on to validate body fluid tests in the absence of a reference method using the example of sodium (Na(+)), potassium (K(+)), and magnesium (Mg(2+)) testing in stool fluid.
Validations of fecal Na(+), K(+), and Mg(2+) were performed on the Roche cobas 6000 c501 (Roche Diagnostics) using residual stool specimens submitted for clinical testing. Spiked recovery, mixing studies, and serial dilutions were performed and % recovery of each analyte was calculated to assess accuracy. Results were confirmed by comparison to a reference method (ICP-OES, PerkinElmer).
Mean recoveries for fecal electrolytes were Na(+) upon spiking=92%, mixing=104%, and dilution=105%; K(+) upon spiking=94%, mixing=96%, and dilution=100%; and Mg(2+) upon spiking=93%, mixing=98%, and dilution=100%. When autoanalyzer results were compared to reference ICP-OES results, Na(+) had a slope=0.94, intercept=4.1, and R(2)=0.99; K(+) had a slope=0.99, intercept=0.7, and R(2)=0.99; and Mg(2+) had a slope=0.91, intercept=-4.6, and R(2)=0.91. Calculated osmotic gap using both methods were highly correlated with slope=0.95, intercept=4.5, and R(2)=0.97. Acid pretreatment increased magnesium recovery from a subset of clinical specimens.
A combination of mixing, spiking, and dilution recovery experiments are an acceptable surrogate for assessing accuracy in body fluid validations in the absence of a reference method.
由于缺乏用于确认准确性的参考方法，对除血液或尿液之外的体液进行检测的验证可能具有挑战性。本研究的目的是评估在没有参考方法的情况下实验室可以依赖的替代准确性评估方法，以粪便液中钠（Na⁺）、钾（K⁺）和镁（Mg²⁺）检测为例。
使用提交用于临床检测的剩余粪便标本，在罗氏cobas 6000 c501（罗氏诊断）上对粪便中的Na⁺、K⁺和Mg²⁺进行验证。进行加标回收率、混合研究和系列稀释，并计算每种分析物的回收率百分比以评估准确性。通过与参考方法（珀金埃尔默公司的电感耦合等离子体质谱仪，ICP - OES）比较来确认结果。
粪便电解质的平均回收率为：加标时Na⁺ = 92%，混合时 = 104%，稀释时 = 105%；加标时K⁺ = 94%，混合时 = 96%，稀释时 = 100%；加标时Mg²⁺ = 93%，混合时 = 98%，稀释时 = 100%。当将自动分析仪结果与参考ICP - OES结果进行比较时，Na⁺的斜率 = 0.94，截距 = 4.1，R² = 0.99；K⁺的斜率 = 0.99，截距 = 0.7，R² = 0.99；Mg²⁺的斜率 = 0.91，截距 = -4.6，R² = 0.91。使用两种方法计算的渗透间隙高度相关，斜率 = 0.95，截距 = 4.5，R² = 0.97。酸预处理提高了一部分临床标本中镁的回收率。
在没有参考方法的情况下，混合、加标和稀释回收率实验的组合是评估体液验证准确性的可接受替代方法。
