Biomarker Helps Prevent COVID-related Blood Clots

red blood cells
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Study shows that patients with moderate COVID and high levels of d-dimer protein are at greater risk of blood clots.

It has become quite clear that SARS-CoV-2 can cause a wide variety of symptoms in infected individuals. As the virus affects multiple organ systems, people often develop thrombosis in both small and large vessels across the body. Previous research had shown the presence of blood clots and thrombosis in more than 70% of COVID patients. Although it can also occur from COVID vaccines, the risk is 8-10 times higher following a COVID infection than vaccines.

COVID-related blood clots often occur in severe infection. However, patients with moderate disease can also develop fatal blood clots. Therefore, there is a need for an effective method to identify those at risk.

Now, a team of researchers have identified a biomarker for predicting the risk of blood clots in moderate COVID patients. Moreover, they discovered an effective treatment for these patients. They published their findings in JAMA Internal Medicine.

The HEP-COVID trial was able to identify an exquisite biomarker—very elevated d-dimer—that not only predicted a high risk COVID-19 inpatient population, but those whose risk was ameliorated by early use of therapeutic heparin anticoagulation for thromboprophylaxis.

Dr. Alex Spyropoulos, study author


The researchers discovered that patients with moderate infection, who are at risk of developing fatal blood clots, have high levels of d-dimer protein. D-dimer forms from the degradation of fibrin, which helps form clots. A simple blood test can determine d-dimer levels and help diagnose clots.

The HEP-COVID trial aimed to compare the efficacy of low-molecular-weight heparin (LMWH) to standard heparin in treating hospitalized moderate COVID patients with high d-dimer levels. Researchers recruited 253 hospitalized COVID patients with d-dimer levels four times the normal upper limit. Results showed that LMWH significantly reduced clot formation and death in these patients. However, researchers did not note a similar benefit in ICU patients.

Nevertheless, study authors believe LMWH should be administered in high-risk hospitalized patients with elevated d-dimers.


Alex C. Spyropoulos et al, Efficacy and Safety of Therapeutic-Dose Heparin vs Standard Prophylactic or Intermediate-Dose Heparins for Thromboprophylaxis in High-risk Hospitalized Patients With COVID-19The HEP-COVID Randomized Clinical Trial JAMA Internal Medicine (2021) DOI: 10.1001/jamainternmed.2021.6203


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