On Sept. 9, 2020, Harvard Medical School investigators at Massachusetts General Hospital reported that patients hospitalized with severe COVID-19 infections who have high levels of the blood clotting protein factor V are at elevated risk for serious injury from blood clots such as deep vein thrombosis or pulmonary embolism. The study results were published in the American Journal of Hematology.

Patients hospitalized with severe COVID-19 infections who have high levels of the blood clotting protein factor V are at elevated risk for serious injury from blood clots such as deep vein thrombosis or pulmonary embolism, according to a new study by Harvard Medical School investigators at Massachusetts General Hospital.

On the other hand, critically ill patients with COVID-19 and low levels of factor V appear to be at increased risk for death from a form of coagulopathy that resembles disseminated intravascular coagulation (DIC)—a devastating, often fatal abnormality in which blood clots form in small vessels throughout the body, leading to exhaustion of clotting factors and proteins that control coagulation.

Their findings, based on studies of patients with COVID-19 in Mass General intensive care units, point to disturbances in factor V activity as both a potential cause of blood clotting disorders with COVID-19 and potential methods for identifying at-risk patients with the goal of selecting the proper anticoagulation therapy.

Importantly, the investigators note that factor V elevation in COVID-19 could cause misdiagnosis of some patients, because under normal circumstances factor V levels are low in the presence of liver dysfunction or DIC. Physicians might therefore mistakenly assume that patients instead have a deficiency in vitamin K.