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 capacity and may support diagnostic and prognostic evaluation in clinical settings. The assay has been widely used in clinical research, but the lack of reference intervals in healthy individuals limits 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 tissue plasminogen activator (tPA) activation (125 ng/mL). Reference intervals were calculated using a non-parametric approach with 90% confidence intervals in accordance with the Clinical and Laboratory Standards Institute (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 min: 33-56 mm, maximum clot firmness: 34-61 mm, lysis index at 30 min: 0-97%, lysis index at 45 min: 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 to 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.