COVID-19,
the disease caused by SARS-CoV-2, is characterized by significant abnormalities
of the hematopoietic as well as the hemostatic system. These abnormalities have
important prognostic as well as therapeutic implications in the management of
these patients. Lymphopenia has emerged as a cardinal manifestation of
COVID-19, which correlates with the severity of the cytokine storm and confers
an adverse prognosis. Although not associated with direct cytopathic effects of
SARSCoV- 2, anemia and thrombocytopenia are commonly present, with increased
incidence in critically ill patients. It has been suggested that an ineffective
adoptive immune response may be responsible for the hyper-inflammatory state
and cytokine response in patients with severe COVID-19. Dysregulation of the
macrophage phenotype may be associated with secondary HLH like physiology with
hyperferritinemia and multi-organ dysfunction. The coagulation abnormalities
are characterized by normal or elevated fibrinogen levels and are distinct from
DIC. This distinct coagulopathy is labelled as COVID coagulopathy. It is
predominant due to local microangiopathy and endothelial dysfunction in
involved organs, such as the pulmonary vasculature. The hypercoagulable state
is associated with a higher risk of arterial and venous thrombosis and a trend
towards an increase in vaso-occlusive events, such as myocardial infarction and
stroke. The D-Dimer elevation is seen in approximately 50% of patients, and increasing
value during hospitalization indicates a poor prognosis. Finally, a comprehensive
understanding of these pathophysiological states may help us in devising
treatment protocols with a combination of antiviral, anti-inflammatory, and anticoagulation
strategies for best treatment outcomes.
Keywords: Acute respiratory distress syndrome, Anticoagulation, COVID-19, Cytokine release syndrome, D-Dimer, Disseminated intravascular coagulation, Endothelial injury, Hematological manifestations, Immunothrombosis, Innate immune system, Low molecular weight heparin, Lymphocytopenia, Microangiopathy, Neutrophilic leukocytosis, NLR Ratio, SARS-CoV2, Thrombocytopenia, Thrombocytosis, Thromboprophylaxis, Venous thromboembolism.