Patients with a severe course of disease showed significantly increased D-dimer concentrations already at admission.3The D-dimer concentration increased massively in severe courses9, 10, 11, 12and was suggested as a predictor for the development of severe acute respiratory distress syndrome (ARDS).13Additionally, increased levels of fibrin degradation products as well as prolonged prothrombin time (PT) were found in nonsurvivors compared with survivors3or compared with healthy controls.14In contrast, data for antithrombin (AT) values are inconsistent. Here, F2 is linked to acute respiratory distress syndrome.