Most people now know that COVID-19 can cause blood clots, potentially leading to paralysis, stroke, heart attack and death.
While it’s not clear precisely how SARS-CoV-2 causes clots, a new study suggests that the amount of a particular protein — called factor V — in a patient’s blood may have something to do with it.
In March, researchers at Massachusetts General Hospital obtained a blood sample from a patient with severe COVID-19 and noticed something unusual. The patient’s blood had significantly above-normal levels of factor V.
Researchers then studied more than 100 patients treated in the intensive care unit for COVID-19.
High levels of factor V were found across the group, and nearly half of the patients had above-normal levels. When researchers compared the samples to historical records, more than 1 in 10 patients had higher factor V levels than had been seen before at the hospital.
“Aside from COVID-19, I’ve never seen anything else cause markedly elevated factor V, and I’ve been doing this for 25 years,” study co-author Dr. Elizabeth Van Cott said in a hospital news release. She is a pathology investigator at Mass General and a pathology professor at Harvard Medical School.
The study found that patients with elevated factor V were more likely to have blood clots in the lungs, called pulmonary embolism, and deep vein thrombosis (DVT), or clots in the veins.
Of patients with high levels of factor V, one-third had either DVT or a pulmonary embolism, compared with 13% of patients with lower levels.
While patients with high factor V levels were at greater risk for clotting problems, patients with lower factor V levels had a higher risk of death, researchers found.
A decrease in factor V levels might indicate patients are progressing to a serious and often fatal condition in which clotting processes become overactive, Van Cott and colleagues said.
They said the findings could help identify which patients are at increased risk of blood clots and death.
The findings were recently published online in the American Journal of Hematology.
There’s more about COVID-19 and blood clots at the Cleveland Clinic.