The Impact of COVID-19 Disease on Platelets and Coagulation

Abstract

Coronavirus disease 2019 (COVID-19) causes a spectrum of disease; some patients develop a severe proinflammatory state which can be associated with a unique coagulopathy and procoagulant endothelial phenotype. Initially, COVID-19 infection produces a prominent elevation of fibrinogen and D-dimer/fibrin(ogen) degradation products. This is associated with systemic hypercoagulability and frequent venous thromboembolic events. The degree of D-dimer elevation positively correlates with mortality in COVID-19 patients. COVID-19 also leads to arterial thrombotic events (including strokes and ischemic limbs) as well as microvascular thrombotic disorders (as frequently documented at autopsy in the pulmonary vascular beds). COVID-19 patients often have mild thrombocytopenia and appear to have increased platelet consumption, together with a corresponding increase in platelet production. Disseminated intravascular coagulopathy (DIC) and severe bleeding events are uncommon in COVID-19 patients. Here, we review the current state of knowledge of COVID-19 and hemostasis.

Keywords: COVID-19; Coagulopathy; D-dimer; Thrombocytopenia; Thrombosis.

Fig. 1

Relationship between platelet count and mean platelet volume (MPV) in a sample of ICU patients affected by COVID-19 (COVID+; n = 10, with 266 measurements) or not (COVID–; n = 10, with 91 measurements). These populations were significantly different from each other (Student's t test, p < 5 ×10⁻⁷).

Fig. 2

Relationship between platelet count and immature platelet fraction (IPF) in a sample of thrombocytopenic ICU patients affected by COVID-19 (COVID+; n = 4, with 23 measurements) or not (COVID–; n = 4, with 23 measurements). a Absolute IPF counts. These populations were significantly different from each other (Student's t test, p < 0.005). b Relative IPF counts. Of note, the relative IPF counts for COVID+ patients did not form a strong enough relationship with platelet count to display a relevant trendline. These populations were significantly different from each other (Student's t test, p < 0.05).