Short- and Long-Term Biological Variation in Cardiac Troponin I Measured with a High-Sensitivity Assay: Implications for Clinical Practice
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- 1 January 2009
- journal article
- Published by Oxford University Press (OUP) in Clinical Chemistry
- Vol. 55 (1), 52-58
- https://doi.org/10.1373/clinchem.2008.107391
Abstract
Background: The improved detection limit and precision in new-generation commercial assays for cardiac troponin I (cTnI) have lowered the 99th-percentile cutoff value, yielding higher frequencies of positive test results. Because serial testing is important in interpreting low concentrations, we evaluated the biological variation of cTnI in both the short (hours) and long (weeks) terms and determined reference change values (RCVs) and the index of individuality (II) for cTnI. Methods: To assess short- and long-term variation, we collected blood from 12 healthy volunteers hourly for 4 h and from 17 healthy individuals once every other week for 8 weeks, measured cTnI with a high-sensitivity assay (detection limit, 0.2 ng/L), and computed analytical, intraindividual, interindividual, and total CVs (CVA, CVI, CVG, and CVT, respectively; CVT = CVA + CVI + CVG) as well as the II. Because of the slight right-skewness of the data, RCVs were calculated with a lognormal approach. Results: Within-day CVA, CVI, and CVG values were 8.3%, 9.7%, and 57%, respectively; the corresponding between-day values were 15%, 14%, and 63%. Within- and between-day IIs were 0.21 and 0.39, respectively. Lognormal within-day RCVs were 46% and −32%, respectively; the corresponding between-day values were 81% and −45%. Conclusions: The low II indicates that population-based reference intervals are less useful for interpreting cTnI values than following serial changes in values in individual patients. This criterion is particularly important for interpreting results from patients who show cTnI increases at low concentrations measured with very high-sensitivity assays, from patients presenting with chest pain (short term), and for evaluating drugs for cardiotoxicity (long term).Keywords
Funding Information
- National Center for Research Resources
This publication has 28 references indexed in Scilit:
- Serial testing of B-type natriuretic peptide and NTpro-BNP for monitoring therapy of heart failure: The role of biologic variation in the interpretation of resultsAmerican Heart Journal, 2006
- Reference Change Values for Brain Natriuretic Peptides RevisitedClinical Chemistry, 2006
- The Biological Variation of C-Reactive Protein in Polycystic Ovarian SyndromeClinical Chemistry, 2005
- Performance Characteristics of 6 Third-Generation Assays for Thyroid-Stimulating HormoneClinical Chemistry, 2005
- Clinical Relevance of Biological Variation of B-Type Natriuretic PeptideClinical Chemistry, 2005
- Diagnostic value of serial measurement of cardiac markers in patients with chest pain: Limited value of adding myoglobin to troponin I for exclusion of myocardial infarctionAmerican Heart Journal, 2004
- Serum 99th Percentile Reference Cutoffs for Seven Cardiac Troponin AssaysClinical Chemistry, 2004
- Predicting Cancer Therapy???Induced CardiotoxicityDrug Safety, 2002
- Myocardial infarction redefined—a consensus document of The Joint European Society of Cardiology/American College of Cardiology committee for the redefinition of myocardial infarctionJournal of the American College of Cardiology, 2000
- Clinical Policy: Critical Issues in the Evaluation and Management of Adult Patients Presenting With Suspected Acute Myocardial Infarction or Unstable AnginaAnnals of Emergency Medicine, 2000