Laboratory evaluation of a new integrative assay to phenotype plasma fibrinolytic system

Background: There is currently no universal and standardized test available to phenotype plasma fibrinolytic system. Aims: Our main aims were to evaluate the performances of the ‘global fibrinolysis capacity’ assay (GFC) performed with the Lysis Timer® instrument, and to study the influence of some preanalytical conditions. Method: Euglobulin clot lysis time (ECLT) and GFC were performed under several preanalytical conditions. Results: GFC showed satisfactory intra- and inter-run precision. Frozen controls and reagents showed stability over the studied period. There was no statistically significant difference between GFC assessed in plasma samples processed at 4 °C or at 20 °C. GFC assessed with frozen-thawed plasma samples was prolonged when compared to fresh samples (p = 0.014). The centrifugation scheme had no influence on PAI-1 activity levels, GFC and ECLT. Reference interval for GFC ranges from 29.3 (C I90% = 26.9–31.9) to 49.5 (90% CI = 45.9–52.2) minutes. In addition, a preliminary study in 40 healthy volunteers and 43 adult patients referred for investigation of a bleeding disorder was conducted to compare GFC and ECLT assays in their ability to classify samples with shortened or prolonged clot lysis times. Disagreements between ECLT and GFC were observed for 23 samples (out of 83), most of them minor. Conclusion: GFC is suitable and convenient for a broad clinical use and can be performed with frozen-thawed plasma samples. Unlike ECLT, GFC is designed to take into account the balance between inhibitors and activators of the fibrinolytic system and could detect both hypo- and hyperfibrinolytic states. Whether it is as suitable as or even better than ECLT to detect a bleeding tendency due to a hyperactive fibrinolytic system deserves to be properly investigated.