Winter Randolph L, Saunders Ashley B, Gordon Sonya G, Miller Matthew W, Fosgate Geoffrey T, Suchodolski Jan S, Steiner Jörg M
Department of Small Animal Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX, USA.
Department of Production Animal Studies, University of Pretoria, Onderstepoort, South Africa.
Vet Clin Pathol. 2017 Jun;46(2):299-307. doi: 10.1111/vcp.12495. Epub 2017 Apr 27.
Biologic variability (BV) is one aspect of interpreting changes in biomarker concentrations known to be clinically important in people with cardiac disease, but it has not been adequately addressed in dogs so far.
The purpose of the study was to determine BV of cardiac troponin I (cTnI) in healthy dogs and dogs with 3 stages of myxomatous mitral valve disease (MMVD).
Healthy dogs and dogs with 3 stages of MMVD were prospectively assigned to groups based on comprehensive clinical evaluation using current guidelines. Concentrations of cTnI were measured hourly, daily, and weekly using standard and high-sensitivity immunoassays. Within- (CV ) and between-subject (CV ) coefficients of variability, percent reference change value (RCV), and index of individuality (IoI) were calculated.
All 10 healthy dogs and 76/112 (68%) of samples from 28 MMVD dogs had cTnI concentrations below the limit of detection (LOD) using a standard sensitivity immunoassay. Only 49/160 (31%) of healthy dog samples and no MMVD samples had cTnI below the high-sensitivity immunoassay LOD. Data analysis for the high-sensitivity immunoassay revealed CV of 48.1%, CV of 60.1%, RCV of 134.0%, and IoI of 0.804 in healthy dogs. In MMVD dogs, CV was 39.6%, CV was 80.7%, RCV was 110%, and IoI was 0.494. Of all MMVD dogs, those with Stage B2 had the lowest RCV of 91%.
Biologic variability affects cTnI concentrations in healthy dogs and dogs with MMVD. Consideration of BV may be clinically relevant when monitoring individual changes in cTnI values, using high-sensitivity immunoassays.
生物变异性（BV）是解释生物标志物浓度变化的一个方面，已知其在心脏病患者中具有临床重要性，但迄今为止在犬类中尚未得到充分研究。
本研究的目的是确定健康犬和患有3个阶段黏液瘤性二尖瓣疾病（MMVD）的犬的心肌肌钙蛋白I（cTnI）的生物变异性。
根据当前指南进行全面临床评估，将健康犬和患有3个阶段MMVD的犬前瞻性地分组。使用标准和高灵敏度免疫测定法每小时、每天和每周测量cTnI浓度。计算组内变异系数（CV）和个体间变异系数（CV）、参考变化值百分比（RCV）和个体指数（IoI）。
使用标准灵敏度免疫测定法，所有10只健康犬以及来自28只MMVD犬的76/112（68%）样本的cTnI浓度低于检测限（LOD）。只有49/160（31%）的健康犬样本和没有MMVD样本的cTnI低于高灵敏度免疫测定法的LOD。高灵敏度免疫测定法的数据分析显示，健康犬的CV为48.1%，CV为60.1%，RCV为134.0%，IoI为0.804。在MMVD犬中，CV为39.6%，CV为80.7%，RCV为110%，IoI为0.494。在所有MMVD犬中，处于B2期的犬的RCV最低，为91%。
生物变异性影响健康犬和患有MMVD的犬的cTnI浓度。在使用高灵敏度免疫测定法监测cTnI值的个体变化时，考虑生物变异性可能具有临床相关性。
