Short- and Long-Term Cardiac Troponin I Analyte Stability in Plasma and Serum from Healthy Volunteers by Use of an Ultrasensitive, Single-Molecule Counting Assay
2009; American Association for Clinical Chemistry; Volume: 55; Issue: 11 Linguagem: Inglês
10.1373/clinchem.2009.128611
ISSN1530-8561
AutoresAlan H.B. Wu, Erin Shea, Quynh-Anh Lu, Jennifer Minyard, Khanh Bui, Jenny Hsu, Sara J. Agee, John A. Todd,
Tópico(s)Cardiac electrophysiology and arrhythmias
ResumoCardiac troponin I (cTnI)1 is the gold standard biomarker for diagnosing patients with acute coronary syndromes. Expert panels have defined the decision limit at >99th percentile of a reference population and assay imprecision of ≤10%. Prototype ultrasensitive cTnI assays allow accurate detection of low concentrations of cTnI in healthy individuals. However, these novel assays require analytical and biological validation before they can be put into clinical practice. We previously reported the 99th percentile cutoff of 7 ng/L for the Erenna® cTnI immunoassay (Singulex), with the requisite precision. Using a single-molecule counting technology, the limit of detection (0.2 ng/L) surpassed many other commercial assays. The improved limit of detection is not an artifact of nonspecific-binding events (1). We also showed that the increased analytical sensitivity of the assay enabled measurement of the short- and long-term biological variation of cTnI from healthy individuals (2). However, to what extent minute levels of analyte instability may have contributed to this variation was not established. We determined the in vitro stability of cTnI in whole blood and serum over short- and long-term intervals in both healthy subjects and in a small subset of patients who presented to the San Francisco General Hospital Emergency Department. A protocol for the use of leftover blood from routine collections and for collecting blood of healthy …
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