Journal of Microbiology & Experimentation Evaluation of The Effect of Storage Temperature on D-dimer Stability, Using Two Different Techniques Submit Manuscript | http://medcraveonline.com Introduction The D-dimer assay evaluates thrombin and plasmin activity and is specific for fibrin derivatives. In this assay, the presence of cross-linked D-dimer domains is a diagnostic marker of fibrin clot lysis. Furthermore, it is a highly sensitive marker for the formation of thrombin and indicates that factor XIII is activated by reactive fibrinolysis. Since fibrinogen derivatives do not contain a cross- linked D-dimer domain, they are not recognized by the D-dimer assay, even when present at high concentrations [1- 4]. D-dimer assay protocols vary among laboratories, with some being superior to others. The method utilized depends not only on the equipment available, but also on a number of other factors including study design and analysis (i.e., chosen cut-off for D-dimer concentrations) [5- 7]. The introduction of bedside analysis of D-dimer concentrations has facilitated rapid and reliable D-dimer tests convenient for clinical use, in which short sample turnaround time is essential. In routine clinical evaluations, D-dimer assays are performed using fresh plasma. However, storage is required in certain cases including reproducibility, reassessment, research, quality assurance purposes, and criminal cases. Although uncommon, testing is delayed in some cases. In all of these cases, proper storage is necessary. D-dimer stability in plasma in vitro is widely assumed but has not yet been documented by systematic studies evaluating samples covering a range of D-dimers. The Clinical and Laboratory Standards Institute (formerly the NCCLS) guidelines state that plasma samples may be stored for up to 2 weeks at -20 °C and up to 6 months at -70 °C [8]. Our study designed to assess the stability of D-dimer levels and storage conditions with two different techniques. To our knowledge, this is the first study to investigate the short-term storage stability of D-dimers in clinical citrated plasma samples containing a range of D-dimer concentrations. Materials and Methods Plasma samples This study was performed by the Department of Clinical Microbiology, Training and Research Hospital, in Sakarya, Turkey from August to November 2014. Samples were collected randomly from 60 patients (31 females and 29 males, age range: 42-58 years) with suspected thromboembolism. Initially, samples were obtained by standard phlebotomy techniques, placed into 5ml tubes containing 3.2% sodium citrate (Vacutainer, Becton Dickinson®, Franklin Lakers, NJ, USA), and then centrifuged (2000g) for 5 min to yield plasma. Eligible samples were defined as those that contained ≥1.5 ml plasma volume. The plasma samples were collected for routine laboratory tests for evaluation of related measurement(s), while the remainder was removed for the D-dimer tests. Plasma sample conditions Prior to the evaluation of D-dimer stability, all plasma samples were aliquoted into eight 200µL plastic sterile storage tubes. Plasma samples were incubated for eight different time intervals (0 (i.e., fresh samples), 4, 24, 48, 72, 120, 168, and 240h) and at three different temperatures (25±2 °C, 4±2 °C, and -20±2 °C) to evaluate the effect of storage conditions on D-dimer stability. As the baseline measurement, fresh plasma samples were tested immediately (0h). Volume 3 Issue 4 - 2016 1 Sakarya University Education and Research Hospital Medical Microbiology Laboratory, Turkey 2 Sakarya University Faculty of Medicine, Department of Microbiology, Turkey *Corresponding author: Engin Karakece, Sakarya University Education and Research Hospital Medical Microbiology Laboratory, Sakarya, Turkey, Tel: 00-90-264- 4445400, 00-90-532-3154942; Email: Received: January 17, 2016 | Published: July 05, 2016 Research Article J Microbiol Exp 2016, 3(4): 00095 Abstract Our study designed to assess the stability of D-dimer levels and storage conditions, using two different techniques. This is the first study to investigate the short-term storage stability of D-dimers in clinical citrated plasma samples containing a range of D-dimer concentrations. This study was performed with 60 samples that were collected randomly patients with suspected thromboembolism. Plasma samples were incubated for eight different time intervals (0 (i.e., fresh samples), 4, 24, 48, 72, 120, 168, and 240h) and at three different temperatures (25+2 °C,4+2 °C, and -20+2 °C) to evaluate the effect of storage conditions on D-dimer stability. Plasma D-dimer concentrations were determined using two different techniques, a fluorescence-based sandwich immunodetection assay (i-CHROMA, Boditech Med Inc., Korea) and an enzyme- linked immunosorbent assay (ELISA) (VIDAS, bioMerieux, France). In accordance with our study, we suggest D-dimer analysis be performed on plasma samples stored for <48h at room temperature. Our findings indicate that i-CHROME and VIDAS D-dimer measurement methods have remarkably high sensitivity and are safe first-line tests that can be utilized to rule out pulmonary emboli in outcome studies multiple freeze-thaw Keywords: D-dimer; Frozen plasma; Fresh plasma; Stability; Room temperature