Comparison of canine cardiac troponin I concentrations as determined by 3 analyzers.
BACKGROUND
Recent interest in cardiac biomarkers has led to the validation of several commercial analyzers for cardiac troponin I (cTnI) evaluation in dogs; however, these analyzers have not been standardized.


OBJECTIVE
It was hypothesized that canine plasma cTnI concentrations as determined by 3 different analyzers would be similar.


METHODS
Twenty-three dogs with cardiac disease were studied.


METHODS
Reconstituted purified canine free cTnI was diluted with canine plasma to 8 concentrations (0.01, 0.1, 0.78, 1.56, 3.13, 6.25, 12.5, and 25 ng/mL), for analysis by 3 analyzers, the Biosite Triage Meter, the Dade-Behring Stratus, and the Beckman-Coulter Access AccuTnI. Plasma samples from 23 dogs with cardiac disease were also analyzed for cTnI concentrations on all analyzers.


RESULTS
Troponin I concentrations in sick dogs were <0.05-5.72 ng/mL (Biosite), 0.02-11.1 ng/mL (Access), and 0.02-9.73 ng/mL (Stratus). Analyzer results were highly correlated with each other (r = 0.97 to 1.0 for purified dilutions, r = 0.61 to 0.89 for samples from dogs); however, the limits of agreement were wide for both purified dilutions and clinical samples. Recovery was highest for the Access (334-1467%) and lowest for the Biosite (38-60%); Stratus 52-233%. Analyzer variability was lowest for the Access (1.2-10.4%) and highest for the Stratus (4.8-33.6%); Biosite 2.8-16.5%.


CONCLUSIONS
Results from this study suggest that although canine cTnI values obtained from the Biosite, Stratus, and Access analyzers are closely correlated, they cannot be directly compared with each other. In the absence of a gold standard none of the analyzers can be considered more correct than the others.
Adin
Darcy B
DB
Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, USA. adind8@yahoo.com
Oyama
Mark A
MA
Sleeper
Margaret M
MM
Milner
Rowan J
RJ
D000818:Animals; D015415:Biomarkers / Q000097:blood; D004283:Dog Diseases / Q000097:blood* / Q000175:diagnosis; D004285:Dogs; D005260:Female; D006331:Heart Diseases / Q000097:blood* / Q000175:diagnosis / Q000662:veterinary*; D007118:Immunoassay / Q000295:instrumentation / Q000662:veterinary*; D016014:Linear Models; D008297:Male; D018709:Statistics, Nonparametric; D019210:Troponin I / Q000097:blood*
D015415:Biomarkers; D019210:Troponin I