Ruaux Craig, Scollan Katherine, Suchodolski Jan S, Steiner Jörg M, Sisson D David
Department of Clinical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis, OR, USA.
Gastrointestinal Laboratory, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX, USA.
Vet Clin Pathol. 2015 Sep;44(3):420-30. doi: 10.1111/vcp.12268. Epub 2015 Jun 23.
The N-terminal fragment of the prohormone B-type natriuretic peptide (NT-proBNP) and cardiac troponin-I are candidate biomarkers for cardiac disease in dogs. The degree of biologic variation in these biomarkers has not previously been reported in healthy dogs or dogs with mitral regurgitation.
The purpose of the study was to derive estimates of intrinsic biologic variability and reference change values for NT-proBNP and cardiac troponin-I in healthy dogs and dogs with mitral regurgitation grade IB and II according to the International Small Animal Cardiac Health Council (ISACHC) grading system.
Plasma and sera were collected weekly for up to 7 weeks from 12 control dogs and 9 dogs with mitral regurgitation. NT-proBNP and troponin-I (C-TnI) concentrations were determined. Indices of biologic variation such as reciprocal index of individuality (r-IoI) and reference change values (RCV) were calculated in both the groups.
Individuality was high in control dogs and dogs with grade IB and II mitral valve regurgitation for both C-TnI (r-IoI 1.6 and 2) and NT-proBNP (1.5 and 2.7), while the 2-sided RCV for NT-proBNP was significantly lower in dogs with mitral regurgitation (52.5% vs 99.4%, P<0.01.).
High individuality of these cardiac biomarkers suggests that, following diagnosis, these assays are best interpreted by serial determination in individual canine patients rather than by comparison to a population-based reference interval. The smaller RCV values for dogs with mitral regurgitation suggest that smaller relative changes in NT-proBNP are clinically meaningful in these patients.
前激素B型利钠肽（NT-proBNP）的N端片段和心肌肌钙蛋白I是犬类心脏病的候选生物标志物。此前尚未报道过这些生物标志物在健康犬或二尖瓣反流犬中的生物学变异程度。
本研究的目的是根据国际小动物心脏健康委员会（ISACHC）分级系统，得出健康犬以及患有IB级和II级二尖瓣反流的犬中NT-proBNP和心肌肌钙蛋白I的内在生物学变异性估计值和参考变化值。
从12只对照犬和9只患有二尖瓣反流的犬中，每周采集血浆和血清，共采集7周。测定NT-proBNP和肌钙蛋白I（C-TnI）的浓度。计算两组中生物学变异指标，如个体性倒数指数（r-IoI）和参考变化值（RCV）。
对于C-TnI（r-IoI分别为1.6和2）和NT-proBNP（分别为1.5和2.7），对照犬以及患有IB级和II级二尖瓣反流的犬个体性均较高，而二尖瓣反流犬中NT-proBNP的双侧RCV显著更低（52.5%对99.4%，P<0.01）。
这些心脏生物标志物的高个体性表明，诊断后，这些检测结果最好通过对个体犬患者进行连续测定来解释，而不是与基于群体的参考区间进行比较。二尖瓣反流犬的RCV值较小，表明NT-proBNP相对较小的变化在这些患者中具有临床意义。
