The conditions that raise the risk of COVID-19 severity are high blood pressure, diabetes, heart disease, cerebrovascular disease, respiratory conditions such as chronic obstructive pulmonary disease (COPD), and conditions affecting the kidneys.
Researchers are still investigating the precise reasons and mechanisms for why these conditions make COVID-19 outcomes so much worse.
The authors of a new review study — appearing in the journal Physiological Reviews — note that hemorrhage or bleeding disorders are among the leading causes of death for these patients.
Dr. Hong-Long Ji, from the University of Texas Health Science Center at Tyler, and his colleagues further suggest in their study that the hyperactivity of the body’s anticoagulant response may be to blame for these bleeding dysfunctions.
An overactive anticlotting system, in other words, may be what causes excessive bleeding in COVID-19.
Why hyperfibrinolysis may be to blame
This overactivity of the body’s attempts to remove blood clots is known as hyperfibrinolysis. Fibrinolysis is “an enzymatic system […] that serves to localize and limit clot formation,” according to research.
In fibrinolysis, a clotting protein called fibrin is broken down, or degraded, through a process that two opposing “forces” drive. These opposite drivers “regulate pro and con the conversion of plasminogen to plasmin, the active enzyme that dissolves the fibrin clot into soluble fibrin degradation products.”
In their paper, Dr. Ji and team note that people with severe COVID-19 also present with fibrin degradation products and reduced platelets, which can be an indication of hyperfibrinolysis.
Hemorrhage in multiple organs together with a positive correlation between fibrinolysis and mortality, say the authors, further support the idea that hyperfibrinolysis may explain mortality in those with preexisting conditions.
Furthermore, COVID-19 patients with diabetes and heart, lung, and kidney preexisting comorbidities will often present high levels of plasminogen and plasmin.
Plasminogen is a nonactive substance in the blood. When substances found in blood vessels’ cells do activate plasminogen, it converts into plasmin — an enzyme that reduces blood clots. However, too much plasminogen and plasmin can cause hemorrhaging.
“Targeting hyperfibrinolysis with a broad spectrum or specific anti-plasmin compounds may prove to be a promising strategy for improving the clinical outcome of patients with comorbid conditions.” – Dr. Hong-Long Ji et al