Preparing for High-Sensitivity Cardiac Troponin Assays
Preparing for High-Sensitivity Cardiac Troponin Assays
All analytical problems will be more critical with hs-cTn assays. Cardiac troponin I (cTnI) and cardiac troponin T (cTnT) are measured using enzyme linked immunosorbent assays. As with all immunoassays, quantification of hs-cTn can be influenced by interference between reagent antibodies and the analyte (cTn), leading to false-positive or negative results. Autoantibodies to cTnI or cTnT are found in 5% to 20% of individuals and can reduce detection of cTn. Additionally, fetal cTn isoforms can be re-expressed in diseased skeletal muscle and detected by the cTnT assays, resulting in false-positive values. Several strategies, including the use of blocking reagents, assay redesign, and use of antibody fragments, have been used to reduce interference. However, these strategies do not completely eliminate them. Furthermore, there are differences in measured cTn values based on specimen type (serum versus heparinized plasma versus EDTA plasma). In addition, hemolysis may affect the accuracy of cTn measurement on some platforms, and it is hard to avoid especially with blood draws from peripheral IV lines, which are common especially in intensive care units.
Analytical Imprecision in Cardiac Troponin Assays
All analytical problems will be more critical with hs-cTn assays. Cardiac troponin I (cTnI) and cardiac troponin T (cTnT) are measured using enzyme linked immunosorbent assays. As with all immunoassays, quantification of hs-cTn can be influenced by interference between reagent antibodies and the analyte (cTn), leading to false-positive or negative results. Autoantibodies to cTnI or cTnT are found in 5% to 20% of individuals and can reduce detection of cTn. Additionally, fetal cTn isoforms can be re-expressed in diseased skeletal muscle and detected by the cTnT assays, resulting in false-positive values. Several strategies, including the use of blocking reagents, assay redesign, and use of antibody fragments, have been used to reduce interference. However, these strategies do not completely eliminate them. Furthermore, there are differences in measured cTn values based on specimen type (serum versus heparinized plasma versus EDTA plasma). In addition, hemolysis may affect the accuracy of cTn measurement on some platforms, and it is hard to avoid especially with blood draws from peripheral IV lines, which are common especially in intensive care units.
