The clinical measurement of serum cardiac troponin I (cTnI) has become one of the most important tools in the diagnosis of acute myocardial infarction and myocardial damage. Unfortunately, considerable variability in clinical cTnI assay results is observed when comparing assays from different manufacturers. With so much variation between assays, physicians and clinical laboratory staff are required to establish their own decision points for cTnI based on the assay used. Standardization of clinical cTnI measurements is needed to provide more reliability in the use of cTnI assays.
Although in 2004 NIST issued SRM 2921 (Human Cardiac Troponin Complex), the use of this certified reference material by assay manufacturers has not led to the desired level of inter-assay comparability. A higher level of troponin I assay standardization has not been achieved because NIST SRM 2921 alone does not provide the complete reference measurement system necessary to improve cTnI measurement quality. What is still needed are matrix-based reference materials and the reference measurement procedures through which certified concentrations of cTnI in matrix reference materials can be determined. Through collaboration with the International Federation of Clinical Chemistry (IFCC), other national metrology institutes, clinical researchers, and cTnI assay manufacturers, reference measurement procedure and serum-based reference materials for cTnI are being developed. Once these materials and methods are established, the components of complete reference measurement system for cTnI will be in place. The impact of this reference measurement system will be a significant improvement in the accuracy and comparability of clinical cTnI assays allowing this important clinical measurement to be used with a higher level of confidence.