Hematological abnormalities in patients with the SARS-CoV-2 (COVID-19) and its prognostic implications

Severe acute respiratory syndrome coronavirus 2 infection conditions a large number of pulmonary and systemic abnormalities that base its physiopathogenesis on immunothrombosis. Specifically, for the area of hematology, from the first clinical and paraclinical characterization studies, hematological and hemostasis abnormalities have been identified that have been consistently documented through different publications and whose knowledge is transcendent from the prognostic point of view. During the course of the disease, longitudinal evaluation of some hematological parameters is essential for the early identification of potentially complicated patients. Absolute leukocyte count, lymphoid depletion, and thrombocytopenia are the principally altered hematologic markers. Severe lymphopenia is a cardinal finding in the early phase of infection, and its persistence during disease progression has a greater adverse prognostic impact. The determination of the neutrophil/lymphocyte and lymphocyte/ platelet hematic indices have also shown their usefulness as predictors of respiratory complications and mortality. A state of hypercoagulability demonstrated by high levels of 0-dimer and or fibrinogen degradation products and various hemostatic alterations in the coagulation profile are associated with a higher rate of morbidity and mortality. Other inflammatory biomarkers including C-Reactive Protein, procalcitonin and ferritin can early identify those cases that require advanced ventilatory and/or hemodynamic support. In this review, the historical antecedents of the pathology and the main hematological and hemostasis alterations and their prognostic implications are addressed.