Effect of Freezing Plasma at –20°C for 2 Weeks on Prothrombin Time, Activated Partial Thromboplastin Time, Dilute Russell Viper Venom Time, Activated Protein C Resistance, and d-Dimer Levels

Abstract

To assess the impact of preanalytical variables of time and temperature on prothrombin time (PT), activated partial thromboplastin time (aPTT), dilute Russell viper venom time (DRVVT), activated protein C resistance (APCR), and d-dimer, samples from 23 healthy individuals and 18 patients having coagulopathy with known abnormal PT and aPTT were collected. Plasma from each individual was separately pooled and aliquoted; the first 2 aliquots were stored at room temperature then analyzed at 2 hours (baseline) and 4 hours postcollection. The remaining aliquots were stored at -20°C and thawed for analysis at 48 hours, 1, and 2 weeks. In both healthy participants and participants with coagulopathy, PT, aPTT, APCR, DRVVT, and D-dimer had no significant changes at 4 and 48 hours, and 1 and 2 weeks postcollection compared to baseline, or the changes were less than 10%. The results indicate PT, aPTT, DRVVT, APCR, and d-dimer can be stored for 2 weeks at -20°C without compromising clinical interpretation in both healthy individuals and individuals with coagulopathy. Increasing storage time will facilitate sample processing from off-site clinics.

Is it acceptable to use coagulation plasma samples stored at room temperature and 4°C for 24 hours for additional prothrombin time, activated partial thromboplastin time, fibrinogen, antithrombin, and D‐dimer testing?

“…For the analysis we chose a percentage change >10% from baseline results as clinically relevant difference between obtained results. The same percentage change was usually adopted by several authors, and according to our knowledge there are still no published guidelines of acceptable percentage changes for clinically relevant difference between results …”

“…To assess the stability of samples, absolute, and percentage changes between results obtained at storage temperatures (RT and/or 4°C), and baseline results were calculated by using the following formula: [(result at storage temperature – baseline result)/baseline result] × 100. Clinically relevant difference was defined as a percentage change >10% …”

“…Global coagulation assays performed in clinical laboratories guide vital patient care decisions in multiple medical disciplines . The most commonly performed coagulation assays in daily routine are prothrombin time (PT), activated partial thromboplastin time (aPTT), fibrinogen (Fbg), antithrombin (AT), and D‐dimer, that are used to assess pathological alterations of the hemostatic system.…”

D-dimer: Preanalytical, analytical, postanalytical variables, and clinical applications

“…Frozen samples may also be used when longer storage periods (i.e. months or years) are needed, especially for research purposes [69][70][71][72].…”

“…All studies published so far used multiple stability criteria except that performed by Betsou et al [70]. The review of D-dimer stability studies showed that a clinical cutoff of 10% was most frequently used [69,71,72,[75][76][77][78]. However, this 10% cutoff has not been derived from biological variation data.…”