Thrombin generation remains stable in frozen plasma over long-term storage

Abstract

Background

The ST Genesia is a fully automated thrombin generation (TG) device. Measuring TG can be useful for medical purposes as it is an indicator for the bleeding or thrombotic risk of a patient. When measuring TG, it is of utmost importance to be careful with the preanalytical part as it can affect TG. One of the preanalytical steps to be cautious with, is the plasma sample storage temperature and duration.

Methods

Citrated blood was collected and centrifuged twice for 10 min at 2840g to obtain platelet poor plasma. Plasma samples were stored directly in the freezer either at −20 °C or at −80 °C. TG was measured with a low, intermediate and high tissue factor concentration (STG-BleedScreen, STG-ThromboScreen and STG-DrugScreen, respectively) in fresh samples and after storage at -20°C and -80°C for 1 day, 1 month, 3 months, 6 months and 12 months. The samples stored at −80 °C were also measured after 18 and 24 months.

Results

Freezing platelet poor plasma samples did affect the TG parameters. This observation was independent of the storage temperature and the tissue factor used for triggering TG. Interestingly, TG was not significantly affected by time in storage at −20 °C and −80 °C even up to one year or two years, respectively. Some variation was observed in the samples measured with thrombomodulin, which may have been due to the use of a reagent kit with different lot number.

Conclusion

Freezing plasma does affect TG independently of the storage temperature. However, once frozen, the TG does not vary significantly in time even up to one or two years for samples stored at −20 °C and −80 °C, respectively.