Preanalytical Storage Does Not Affect 99th Percentile Cardiac Troponin T Concentrations Measured with a High-Sensitivity Assay

To the Editor:On the occasion of the introduction of the high-sensitivity cardiac troponin T (hs-cTnT)1 (fifth-generation) assay from Roche Diagnostics and considering the importance of a stable 99th percentile upper reference limit for early diagnosis of acute myocardial infarction (1), we evaluated the impact of various preanalytical storage conditions on cTnT concentrations around the 99th percentile (14 ng/L). The stability of cTnT as measured with the fifth-generation hs-cTnT assay has previously been shown (2, 3); however, the storage conditions and cTnT concentrations evaluated in these studies were limited.In this study, we investigated the most common routine storage conditions for whole blood, serum, and heparin-treated plasma. We obtained samples from 90 patients admitted to the catheterization laboratory for suspected minor myocardial damage. We used multiple samples from individual patients instead of pooled serum to prevent masking of possible matrix effects and to study a wider range of cTnT concentrations. Approval was given by the Medical Ethical Committee of Amphia Hospital, Breda, the Netherlands. All subjects gave written informed consent.For evaluating the effect of storage of whole blood, we collected venous blood from 30 participants into 3 serum tubes each (10-mL Venosafe™ Plastic Tubes, Serum Gel; Terumo) and 3 …