title: Standardization of troponin I measurements: an update.
abstract: Standardization of cardiac troponin I (cTnI) measurement is important because of the central role for diagnosis of myocardial infarction. In blood, cTnI is present as a heterogeneous mixture of different molecular species. The analytical problem caused by this heterogeneity may be circumvented by recognition of a unique, invariant part of the molecule that is common to all components of the mixture. Antibodies used for the development of cTnI assays should selectively recognize epitopes within this invariant part, leading to a consequential increase in the homogeneity of immunoassay reactivity. This should be associated with the use of a reference material that represents the natural and major antigen in blood after tissue release, i.e., the troponin complex. Although a primary reference material for cTnI is available, studies indicate that cTnI assays remain without harmony after recalibration using this material. To achieve closer comparability of cTnI values between assays, the use of a secondary reference material, consisting of a panel of human serum pools, is proposed for use by manufacturers to calibrate their assays. To assign true cTnI concentration values to this secondary reference material, establishment of a reference measurement procedure for cTnI is required. A practical approach to the development of a reference procedure could be to design an immunochemical assay with well-characterized specificity to the invariant part of the cTnI molecule and calibrated using the primary reference material.
authors.affiliation: Center for Metrological Traceability in Laboratory Medicine (CIRME), University of Milan, Milano, Italy. sd.chair@ifcc.org
authors.forename: Mauro
authors.initials: M
authors.lastname: Panteghini
authors.forename: David M
authors.initials: DM
authors.lastname: Bunk
authors.forename: Robert H
authors.initials: RH
authors.lastname: Christenson
authors.forename: Alexei
authors.initials: A
authors.lastname: Katrukha
authors.forename: Robert A
authors.initials: RA
authors.lastname: Porter
authors.forename: Heinz
authors.initials: H
authors.lastname: Schimmel
authors.forename: Lili
authors.initials: L
authors.lastname: Wang
authors.forename: Jillian R
authors.initials: JR
authors.lastname: Tate
mesh_terms: D002138:Calibration; D019963:Clinical Chemistry Tests / Q000379:methods / Q000592:standards; D006801:Humans; D007118:Immunoassay / Q000592:standards; D009203:Myocardial Infarction / Q000097:blood / Q000175:diagnosis; D012015:Reference Standards; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D019210:Troponin I / Q000097:blood* / Q000276:immunology
chemical_list: D019210:Troponin I