FXIII-A₂ level correlates with FXIIIa activity and FXIII-A₂B₂ level after rFXIII-A₂ infusion in humans. Spearman correlations between FXIII-A₂ antigen and (A) FXIIIa activity or (B) FXIII-A₂B₂ antigen in human plasma after infusion of 35 IU/kg rFXIII-A₂ (mentor2 trial). Each dot represents 1 measurement; the lower limit of detection for FXIII-A₂ antigen was 0.845 μg/mL.