D-Dimer, Fibrinogen, and IL-6 in COVID-19 Patients with Suspected Venous Thromboembolism: A Narrative Review

Coronavirus disease 2019 (COVID-19) emerged from the West District of Southern China Seafood Wholesale Market in late December 2019 and has been declared a global pandemic by the World Health Organization (WHO). Infection with severe acute respiratory syndrome coronavirus (SARS-CoV-2) presents with upper respiratory symptoms like cough, fever, and lethargy. At the same time, in later stages, critical COVID-19 patients develop acute respiratory distress syndrome (ARDS), venous thromboembolism (VTE), and multiple organ failure from cytokine storm and coagulation hyperactivity. Primary manifestations of thrombotic events include deep vein thrombosis (DVT), disseminated intravascular coagulation (DIC) and pulmonary embolism (PE). Initial coagulopathy in COVID-19 patients presents with elevated fibrin degradation products, especially D-dimers. In contrast, late presentations show evidence of prolonged prothrombin time (PT) and activated partial thromboplastin (aPTT), increased platelets, and fibrinogen levels. Diagnosis and monitoring of disease progression are done by regular screening of laboratory parameters, including D-dimer and fibrinogen. Management of coagulopathy in COVID-19 patients is like that of critically ill patients, including thromboprophylaxis. Coagulopathy is a poor prognostic factor, and optimum strategies should be developed for early diagnosis, prevention, and prompt treatment of VTE in COVID-19 patients. Thrombosis prophylaxis with low molecular weight heparin (LMWH) has shown beneficial results in preventing coagulopathy a reducing risk of mortality due to thrombotic events. We will discuss VTE in COVID-19 patients highlighting the role of D-dimer, fibrinogen, and interleukin-6 (IL-6).