Falsely elevated troponin I attributed to collection tubes using the Vitros ECiQ system

Abstract

Cardio-specific troponins (i.e., cTnI and cTnT) have become the mainstay for diagnosing and monitoring myocardial damage (1, 2). However, false-positive results for cTnI have been reported, primarily caused by interferents, such as heterophilic antibodies, rheumatoid factor, macrocomplexes, hemolysis and fibrin (3–5). Recently, falsely elevated cTnI attributed to inadequate centrifugation have been reported (6). We have observed another potential source of false positive results attributed to collection tubes. Our study was performed in the Laboratory Medicine Center, Affiliated Hospital of Nantong University, and the ethical approval was obtained from the Research Ethical Committee, College of Medicine, Nantong University. Our objective was to assess whether serum/plasma samples were adequate for the assay of cTnI using the Vitros ECiQ Immunodiagnostic system (Ortho Clinical Diagnostics, Inc., USA). Blood samples were obtained from 86 apparently healthy volunteers and collected in separator gel clot activator tubes (cat no. 230811, lots L090315, KeHua, Shanghai, China), lithium heparin tubes (cat no. 230517, lots 090102, KeHua) and lithium heparin with gel separator tubes (cat no. 230911, lots 090408, KeHua). The blood collection tubes were inverted eight times to ensure thorough mixing. All samples were centrifugated at 2000 g for 10 min and analyzed using the Vitros ECiQ system with the manufacturer’s reagents. The cTnI concentration ranges were 0.000–2.257 mg/L (separator gel clot activator tube), 0.000–0.031 mg/L (lithium heparin tube) and