Biological Variation of Cardiac Troponin: Why It Matters for Diagnostic Thresholds and Serial Testing
High-sensitivity cardiac troponin assays exhibit favorable biological variation profiles, with a low intra-individual index of variation (<0.6) and analytical imprecision of approximately 5% CV at the 99th percentile cutoff. Reference change values above 30% between serial measurements can be considered statistically significant, substantially improving the accuracy of acute coronary syndrome diagnosis in the emergency department. These characteristics also support emerging applications in cardiovascular risk screening among high-risk populations, though optimal target groups and preventive strategies require further study.
The original study
Clinical relevance of biological variation of cardiac troponins.
- Authors
- Clerico A, Padoan A, Zaninotto M, Passino C, Plebani M
- Journal
- Clinical chemistry and laboratory medicine
- Type
- Journal Article, Review
- PMID
- 33554558
Original abstract
The high-sensitivity immunoassays for cardiac troponin I (hs-cTnI) and cardiac troponin T (hs-cTnT) are recommended by all the most recent international guidelines as gold standard laboratory methods for the detection of myocardial injury and diagnosis of acute myocardial infarction (AMI). In this review article, the Authors aimed at discussing the relevant biochemical, physiological, and clinical issues related to biological variability of cTnI and cTnT. Cardiac troponins, measured with hs-cTn methods, show a better clinical profile than the other cardio-specific biomarkers (such as the natriuretic peptides, BNP and NT-proBNP). In particular, the hs-cTn methods are characterized by a low intra-individual index of variation (<0.6) and reduced analytical imprecision (about 5% CV) at the clinical cut-off value (i.e., the 99th percentile URL value). Moreover, recent studies have reported that differences between two hs-cTn measured values (RCV) >30% can be considered statistically significant. These favourable biological characteristics and analytical performance of hs-cTn methods significantly improved the accuracy in the diagnostic process of acute coronary syndromes (ACS) in patients admitted to emergence department. In addition, several studies have demonstrated the clinical usefulness of cardiovascular risk evaluation with hs-cTn methods in some groups of patients with clinical conditions at high cardiovascular risk (such as systemic hypertension, severe obesity, diabetes mellitus, renal insufficiency, and chronic obstructive pulmonary disease). However, screening programs in the general population with hs-cTn methods for cardiovascular risk stratification require further investigation to define the optimal target populations, timing of measurement, and preventive interventions.