Analytical evaluation of an automated immunoassay for cardiac troponin I: the Vidas Troponin I assay.
Cardiac troponin I (cTnI) is a sensitive and specific biochemical marker of myocardial damage. We assessed the analytical performance of the Vidas Troponin I assay (Biomerieux). Controls and serum pools were used to determine the precision, analytical sensitivity and linearity; 97.5 and 99.5 percentiles concentrations were determined from the reference population. Fifty corresponding samples of serum and plasma (lithium-heparin) were tested and the results compared. The in vitro stability of serum and plasma samples was assessed at 20 degrees C, 4 degrees C and -20 degrees C, respectively. Samples of serum were used to assess the agreement between the Vidas Troponin I method and the revised Dimension RxL cTnI method (Dade-Behring). The total imprecision (CVs) was 13.1-5.2% for concentrations ranging between 0.25 and 19.8 microg/l cTnI. The lower detection limit was <0.1 microg/l. The upper reference limit (97.5 and 99.5 percentiles) was 0.11 microg/l and 0.12 microg/l, respectively (CV > 10%). The assay was linear up to 21 microg/l. The concentrations in lithium-heparin plasma were higher compared to those of the matched serum samples. The study of the agreement between the Vidas and Dimension RxL cTnI assays showed a total concordance of 96% with a bias value of -0.042. The Vidas Troponin I test is a fast, precise and sensitive method for the determination of cTnI.
Unità Operativa di Patologia Clinica I, Policlinico di Bari, Bari, Italy. diseriofrancesca@tiscali.it
Francesca
F
Di Serio
Paolo
P
Trerotoli
Gabriella
G
Serio
Lucia
L
Varraso
Nicola
N
Pansini
D001331:Automation; D006801:Humans; D007118:Immunoassay / Q000379:methods* / Q000592:standards; D009206:Myocardium / Q000378:metabolism*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D019210:Troponin I / Q000097:blood*
D019210:Troponin I