Researchers found that this blood abnormality was four times more likely in those experiencing difficulties with basic exercise.
Patients suffering from long COVID may face an increased risk of abnormal blood clotting, according to a new study.
The study at University College London Hospitals NHS Foundation Trust and University College London and published in the journal Blood Advances measured clotting markers by assessing the relative levels of two proteins in the body.
They analyzed the ratio of Von Willebrand factor (VWF), a protein important in blood clotting, to ADAMTS13, a protein that cuts or splices VWF to prevent it from clogging blood vessels.
If there was significantly more VWF than ADAMTS13 in the bloodstream, scientists characterized patients as being in a pro-thrombotic state, meaning that they could face a greater risk of developing blood clots.
Impaired exercise capacity.
Researchers also found that this blood abnormality was four times more likely in those experiencing difficulties with basic exercise more than 12 weeks after their COVID-19 infection.
Researchers measured oxygen levels and tested participants’ blood before and after exercise to measure their lactate levels, which helped describe participant response to exertion.
During exercise, the body converts glucose into energy using oxygen. However, when oxygen levels are depleted, the body starts producing lactate instead, which can be turned into energy without oxygen.
In the study, patients who exhibited a significant decrease in oxygen levels while exercising and/or a rise in lactate afterward were said to demonstrate an impaired exercise capacity.
Notably, patients with raised levels of blood clotting markers were also four times more likely to have an impaired exercise capacity.
“By definition, this syndrome occurs when one experiences COVID-related symptoms long after the onset of infection that we can’t attribute to any other cause or diagnosis,” explained study author Dr Nithya Prasannan, of the Department of Haematology at UCLH.
“This study offers us laboratory and clinical evidence to begin to understand why some people experience long COVID symptoms.”
In the future, Dr. Prasannan and her colleagues aim to assess patient bloodwork using different research platforms over the course of their long COVID illness to assess how their risk of thrombosis might change with the progression of their symptoms.
“I hope that people will view this research as a step forward in understanding what causes long COVID, which will hopefully help us guide future treatment options,” explained Dr. Prasannan.