In some cases of COVID-19, especially in those where rapid worsening of the disease is observed, it has been observed that infection by the new coronavirus may increase the risk of thromboembolic diseases such as stroke, pulmonary embolism and disseminated intravascular coagulation, in which blood begins to clot throughout the body.
This is because, in some people, the immune response occurs in an exacerbated way, leading to an excessive activation of lymphocytes, contributing to the increase of thrombin, responsible for blood clotting.
It is thought that this exaggerated reaction of the immune system may be related to macrophage activation syndrome, having been verified in apparently young adults without associated health conditions, who had a fatal outcome due to the occurrence of thromboembolic episodes.
What is Macrophage Activation Syndrome?
Macrophage Activation Syndrome consists of an excess of immune system activation, leading to uncontrolled T-cell production, excessive macrophage activation, and exaggerated release of pro-inflammatory cytokines.
Generally, the diagnosis consists of the detection of ferritin, which is a parameter that is elevated in the presence of an exacerbated immune response.
What is the relationship between immune response and thromboembolic diseases?
The uncontrolled response of macrophages seems to contribute to an uncontrolled increase in thrombin, which is a protein that intervenes in blood clotting.
Thus, high levels of thrombin will lead to increased formation of blood clots, increasing the chances of suffering from thrombotic phenomena. When clots reach the lung, they can cause a pulmonary embolism and, when they reach the brain, they can lead to the occurrence of a stroke.
In addition, some more critical covid-19 patients develop disseminated intravascular coagulation, which consists of blood clotting throughout the body, leading to thrombus formation.
Diagnosis can be made by dosing the D-dimer into the blood, which is elevated in the presence of thrombi.
How treatment is done
COVID-19 is a recent disease and many of the treatments are being tested all over the world.
In these cases, anticoagulants are being administered, namely heparin, which acts by blocking the pathological activation of thrombin, preventing blood clotting.
In addition, another substance, methotrexate, has also been associated, which is able to control the exacerbation of the immune response.