Common hematological abnormalities due to COVID-19 infection include thrombocytopenia, lymphopenia, altered coagulation, and disseminated intravascular coagulation (DIC). Thrombocytopenia occurring in 5–21% of COVID-19 patients is more severe in patients with more severe disease.
Collectively, severe inflammation in severe COVID-19 causes adverse hematological effects, including reduced hemoglobin levels, but significant changes in hemoglobin levels or hematocrit have not been reported in mild to moderate COVID-19. About 20–40% of COVID-19 patients have leukopenia, and 3–24% have leukocytosis. There is a strong association between lymphocytopenia and COVID-19.
