Abstract
Background: Multiple cardiac troponin I (cTnI) immunoassays are commercially available. Overall, assays have not been standardized, and inter-assay differences in the detection of the analyte cardiac troponin I can be clinically relevant.Objective: To compare the diagnostic accuracy of the commercially available Abbott i-STAT®1 cTnI immunoassay (i-STAT) and the previously validated ADVIA Centaur TnI-Ultra immunoassay (Centaur) in cattle.Hypothesis: There will be significant differences in bovine serum cTnI results measured by the Centaur and i-STAT methods.Animals: Ten dairy cows with experimentally induced myocardial injury due to monensin administration. Thirty apparently healthy dairy cows with no history of monensin exposure served as controls.Methods: Blood was collected at various time points after administration of a single dose of monensin (20 to 50 mg/kg) via orogastric tube. A total of 112 blood samples were collected. Cardiac TnI concentration was analyzed with the two methods and the association between methods analyzed via linear regression. Bland-Altman analysis to evaluate agreement between methods was performed on samples divided into groups (cTnI < 1.0 ng/mL and cTnI ≥ 1.0 ng/mL).Results: Analyzer results were linearly correlated with each other (R2 = 0.931). Samples with cTnI concentrations <1.0 ng/mL had a bias of −0.13 ± 0.20 ng/mL and samples with cTnI concentrations >1.0 ng/mL had a bias of −9.81 ± 13.26 ng/mL.Conclusions and clinical importance: The results of this study reveal that cTnI concentrations determined with the i-STAT are systematically lower compared to the concentrations determined by the Centaur.
Highlights
Cardiac troponin I is a sensitive and specific biomarker for the detection of myocardial injury in humans
Sixty-eight samples had a Cardiac troponin I (cTnI) concentration above the lower limit of detection of the Centaur assay and 55 samples had measurable concentrations via the i-STAT
The results of this study indicate that the concentrations of cTnI determined by each analyzer were not equal, as the i-STAT point-of-care analyzer consistently yielded concentrations less than the previously validated Centaur analyzer
Summary
Cardiac troponin I (cTnI) is a sensitive and specific biomarker for the detection of myocardial injury in humans. Infection with Theileria annulata in cattle is associated with increased circulating cTnI [20]. Multiple toxicities have been reported to increase cTnI in ruminant species, ranging from plants such as Rayless Goldenrod (Isocoma pluriflora), [21] to anti-inflammatories such as diclofenac [22], as well as the ionophore antibiotics, such as monensin [23,24,25]. Any increased blood concentration of cTnI is an indicator of myocardial injury and has been associated with an adverse clinical outcome in human patients [26], as well as downer cattle [27]. Multiple cardiac troponin I (cTnI) immunoassays are commercially available. Assays have not been standardized, and inter-assay differences in the detection of the analyte cardiac troponin I can be clinically relevant
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