title: Cardiac Troponin Assays: Guide to Understanding Analytical Characteristics and Their Impact on Clinical Care.
abstract: BACKGROUND
  Cardiac troponin I (cTnI) and cardiac troponin T (cTnT) determinations are fixtures in clinical practice and research. Cardiac troponin testing has been the standard of practice for the diagnosis of acute myocardial infarction (AMI), early rule-out, risk stratification, and outcomes assessment in patients presenting with acute coronary syndrome (ACS) and non-ACS myocardial injury. We recognize from reading the literature over the past several years how poorly understood the analytical characteristics are for cTnI and cTnT assays by laboratorians, clinicians, and scientists who use these assays.
  
  
  BACKGROUND
  The purposes of this mini-review are (a) to define limit of blank, limit of detection, limit of quantification, and imprecision, (b) overview the analytical characteristics of the existing cardiac troponin assays, (c) recommend approaches to define a healthy (normal) reference population for determining the 99th percentile and the appropriate statistic to use for this calculation, (d) clarify how an assay becomes designated as "high sensitivity," and (e) provide guidance on determining delta (Δ) change values.
  
  
  CONCLUSIONS
  This review raises important educational information regarding cTnI and cTnT assays, their 99th percentile upper reference limits (URL) differentiated by sex, and specifically addresses high-sensitivity (hs)-assays used to measure low concentrations. Recommendations are made to help clarify the nomenclature and analytical and clinical characteristics to define hs-assays. The review also identifies challenges for the evolving implementation of hs-assays into clinical practice. It is hoped that with the introduction of these concepts, laboratorians, clinicians and researchers can develop a more unified view of how these assays should be used worldwide.
authors.affiliation: Department of Laboratory Medicine and Pathology, Hennepin County Medical Center, and University of Minnesota, Minneapolis, MN; apple004@umn.edu.
authors.forename: Fred S
authors.initials: FS
authors.lastname: Apple
authors.affiliation: Division of Cardiology, Department of Medicine, Hennepin County Medical Center and Minneapolis Heart Institute, Abbott-Northwestern Hospital, Minneapolis, MN.
authors.forename: Yader
authors.initials: Y
authors.lastname: Sandoval
authors.affiliation: Mayo Clinic and Mayo College of Medicine, Rochester, MN.
authors.forename: Allan S
authors.initials: AS
authors.lastname: Jaffe
authors.affiliation: Servei Bioquimica, IBB-Hospital de la Santa Creu i Sant Pau and Department de Bioquimica i Biologia Molecular, Universitat Autònoma, Barcelona, Spain.
authors.forename: Jordi
authors.initials: J
authors.lastname: Ordonez-Llanos
mesh_terms: D054058:Acute Coronary Syndrome / Q000175:diagnosis*; D006801:Humans; D009203:Myocardial Infarction / Q000175:diagnosis*; D015427:Reperfusion Injury / Q000175:diagnosis*; D019210:Troponin I / Q000032:analysis*; D020107:Troponin T / Q000032:analysis*
chemical_list: D019210:Troponin I; D020107:Troponin T