D-dimer and COVID-19
Thromboembolism of COVID-19 patients is the fatal sequelae of hyper-coagulation and fibrinolytic abnormalities. Pulmonary embolism and deep vein thrombosis (DVT) can cause respiratory failure in severely ill patients with COVID-19. After death pathology shows that small fibrinous thrombi in small pulmonary arterioles are very common. Activation of the coagulation cascade is further supported by endothelial tumefaction, pulmonary megakaryocytes in the capillaries, and endotheliitis. Elevated D-dimer is an indicator of the activation of the fibrinolysis system and removal of clots or extravascular collections of fibrin by plasmin [8].
Increased D-dimer level has not consistently been observed by all COVID-19 clinical studies, although it is a broadly applied biomarker for prognosis and outcomes of anti-thrombosis. There is strong positive association of elevated D-dimer on admission with mortality, indicating the prognostic value of an elevated D-dimer for the high risk of death. There is positive correlation between D-dimer and days from onset to admission, the need for ventilation and the days are taken for PCR test reversion to negative. Data shows that prompt admission and clearance of the SARS-CoV-2 virus may alleviate the severity and reduce fatal events by preventing hyper-fibrinolysis and inflammation.
D-dimer and other clinical variables’ associations indicate either a relationship that could be cause-effect or indirect. Few D-dimer-associated variables have been confirmed as prognostic biomarkers for developing fatal events and in-hospital mortality. Extremely elevated plasma D-dimer seems to be the consequence of hyper-fibrinolysis predominately in the pulmonary capillaries and other organs. And a dynamic increase in the D-dimer level may be associated with thromboembolism and higher fatality, while we infer that a continuous decline by daily testing will generally lead to recovery. D -dimer was positively associated with the severity of lung injury, the days from the onset to admission, onset to dyspnea, time is taken to be PCR negative, and overall mortality. Finally, the variables were significantly associated with D-dimer were respiratory rate, systolic pressure, dyspnea, serum K+, neutrophils, globulin, CRP, ferritin, blood glucose, total bilirubin, mortality, ventilation, sepsis, and acute cardiac injury [9].
The coagulopathy and abnormal results in coagulation tests have become common features reported in patients with COVID-19 from the very early days of the emergence of the new coronavirus strain. COVID-19-dependent coagulopathy gained attention when PT, aPTT, fibrinogen, and D-dimer tests were recommended by researchers to evaluate the proper homeostasis of the system associated with the prognosis of patients. The prophylactic use of anticoagulants was proven to be effective in lowering the mortality rate and highlighted the role of the coagulation system in COVID-19. The link between thrombosis and COVID-19 as an inflammatory disease has been investigated [10].