Excessive blood clotting is a recognised feature of severe COVID-19, but a new study suggests that some hospitalised patients may also be vulnerable to bleeding, which is associated with an increased risk of death.
According to medicalnewstoday.com, the study which was published in the journal, Scientific Reports, was conducted by researchers at Michigan Medicine and the University of Michigan in Ann Arbor, United States of America.
“After an injury, clotting prevents dangerous loss of blood. Blood clots, or “thrombi,” can also block blood vessels, however, with potentially fatal consequences.
“Normally, our blood maintains a delicate balance between its tendency to form clots and its tendency to break them down. In particular, the body does this by continually adjusting the activity of a protein in the blood called plasminogen, which promotes the breakup of blood clots, or “thrombolysis.”
“The body performs this balancing act by changing the levels of two other proteins circulating in the bloodstream, known as tissue plasminogen activator (TPA) and plasminogen activator inhibitor-1,” the researchers wrote.
Early in the pandemic, research began to show that the blood of critically ill patients with COVID-19 is unusually “sticky” or prone to clotting, with potentially fatal consequences including deep vein thrombosis, stroke, and heart attack.
These findings led to the practice of giving high doses of anticoagulant drugs — which work in various ways to prevent the development of blood clots — to patients hospitalised with COVID-19 throughout their treatment.
The study authors, however, suggested that the findings may not be the best approach for all patients.
They measured levels of TPA and plasminogen activator inhibitor-1 in the blood of 118 patients hospitalised with COVID-19 as well as 30 healthy controls.
They found very high levels of both proteins in the blood of these patients. These proteins were associated with respiratory difficulties, but high levels of TPA had stronger correlations with mortality.
In the laboratory, the researchers also tested the tendency of the blood samples to clot by adding an enzyme called thrombin that promotes clotting.
This showed that very high levels of plasminogen activator significantly enhanced the tendency to break down blood clots.