Reference Intervals for ROTEM ® -tPA: Whole-Blood Fibrinolysis Assessment in Healthy Adults

Background: Fibrinolysis is essential for maintaining hemostatic balance, and disturbances contribute to bleeding and thrombotic disorders. Rotational thromboelastometry modified with tissue plasminogen activator (ROTEM®-tPA) enables dynamic assessment of fibrinolytic activity and may support diagnostic and prognostic evaluation in clinical settings. The assay has been widely used in clinical research, but lack of reference intervals in healthy individuals limit standardized interpretation and clinical implementation.Methods: We included 122 healthy plasma donors aged 20-69 years with equal sex distribution. Citrated whole blood samples were analyzed using a standardized ROTEM®-tPA protocol with exogenous tPA activation (125 ng/ml). Reference intervals were calculated using a non-parametric approach with 90% confidence intervals in accordance with CLSI EP28-A3c guidelines. Analytical repeatability (coefficients of variation) and associations with age and sex were also evaluated.Results: ROTEM®-tPA parameters demonstrated consistent performance across age groups and sex. Analytical repeatability was high, reflected by low coefficients of variation. Reference intervals were established for all ROTEM®-tPA parameters. For key parameters, reference intervals were: clotting time 45-68 s, amplitude at 10 minutes 33-56 mm, maximum clot firmness 34-61 mm, lysis index at 30 minutes 0-97%, lysis index at 45 minutes 0-50%, maximum lysis 92-100%, area under the curve 3429-6025 mm•100, lysis time 1412-3211 s, lysis onset time 720-2182 s, fibrinolysis speed 2-6 mm/min, and time to area under the curve initiation 404-1314 s.Conclusion:We established the first comprehensive reference intervals for ROTEM®-tPA in a healthy adult population. These data provide a foundation for standardized interpretation of fibrinolytic dynamics and support clinical application of ROTEM®-tPA in bleeding and thrombotic disorders.