Coronavirus Disease 2019: Hematological Anomalies and Antithrombotic Therapy

After the first cases of COVID-19 appeared in Wuhan, China at the end of 2019, the disease quickly become a pandemic that has seriously affected the economic and health systems in more than 200 countries and territories around the world. Although most patients have mild symptoms or are even asymptomatic, there are patients who can develop serious complications such as acute respiratory distress syndrome or venous thromboembolism requiring mechanical ventilation and intensive care. Hence, it is important to identify patients with a higher risk of complications in a timely manner. Thus, the objective of this paper is to review the hematological laboratory parameters that consistently are altered in COVID-19 and to identify their relationship with the severity of the disease. According to 11 selected reports, the frequency of patients aged > 65 years is higher among subjects severely affected or deceased; likewise, males predominantly suffer from comorbidities such as hypertension, diabetes or obesity. Retrospective studies have identified alterations in various hematological and inflammatory parameters as part of the host's response to infection and a secondary increased risk of different thrombotic events. Among these altered parameters, D-dimer, C-reactive protein, and interleukin-6 have been tested as prognostic biomarkers due to their close relationship with the severity of the disease. Actually, they can reliably indicate the use of antithrombotic therapy at prophylactic or therapeutic doses (mainly D-dimer), as has already been established in those patients who, after an individualized assessment, appear to be at high risk for thrombotic events.