Introduction. It is known that patients with acute coronavirus disease have prothrombotic and hypercoagulable complications, but potential long-term changes in the hemostasis system have not been studied. Despite the recovery, many patients who have suffered from COVID-19 often have hemostasiological disorders during 27-49 weeks. Usually, patients turn to a hematologist because of bleeding, various skin hemorrhages, and thrombosis. A thorough examination of such patients reveals disorders in the hemostasis system, which may develop during post-covid syndrome such as SARS-CoV-2-associated endothelial dysfunction and microangiopathy.

Aim. To investigate changes in hemostasis system parameters in patients with COVID-19 to identify diagnostic criteria for confirming post-covid syndrome.

Materials and methods. 45 patients were examined in the post-covid period (among them 25 women and 20 men, patients aged 18 to 82). The diagnosis in all patients included in the study was confirmed by the PCR method. D-dimer, fibrinogen, prothrombin time (PT), thrombin time (TT), and activated partial thromboplastin time (APTT) in the blood plasma of patients were determined to assess the state of hemostasis.

Results. The analysis of the data of the examined patients indicates that thrombotic complications were more often registered than hemorrhagic complications. 16 patients with hemorrhagic complications had changes in the primary link of hemostasis, and plasma hemostasis indicators were within the reference interval. It was established that the majority of patients had an increase in D-dimer levels (in 37 patients), amounting to an average of 1.48 ± 0.9 μg/ml. In 8 patients, D-dimer was within the normal range (0.41 ± 0.1 μg/ml), despite clinical manifestations of disorders in the hemostasis system. An increase in fibrinogen values (from 360 mg/dL to 673 mg/dL) was in 39 patients, which was 526.5 ± 10.9 mg/dL on average. In addition, APTT was increased in 5 patients (from 35.7 to 37.0 sec), and PT – in 7 people (from 16.6 to 18.2 sec). An isolated increase of D-dimer and fibrinogen without significant changes in PT and APTT after six months or more after COVID-19 in patients without oncology and other inflammation processes can be signs of the post-covid syndrome.

Conclusions.Changes in the hemostasis system that appeared during acute COVID-19 can persist for 12 months or more after recovery. Hemostasiological disorders may be detected for the first time after a long time (12 months or later) in patients suffering from COVID-19. Prothrombotic changes in the hemostasis system are registered more often than hypocoagulable and can lead to threatening thrombotic complications in patients who have suffered from COVID-19. The severity of acute period COVID-19 does not always correlate with the detected hemostasiological disorders. Indicators of D-dimer and fibrinogen are important measures for diagnosis or confirmation of post-covid syndrome. Control of PT, АPTT, and TT is necessary for patients who have suffered from COVID-19 to differentiate other pathologies.

Keywords: COVID-19, D-dimer, thrombosis, fibrinogen.