Severe COVID-19 seems to interact with the von Willebrand Factor (VWF)-ADAMTS13 axis in unknown ways to increase the risk of thrombotic disease, according to a recent letter to the editor published in the Journal of Thrombosis and Haemostasis.

COVID-19 puts people at increased risk for thrombotic disease that does not respond to therapeutic anticoagulation. Some studies have found elevated levels of VWF activity, VWF antigen, and Factor VIII levels. A recent study found that the VWF-ADAMTS13 axis may be correlated with disease activity in COVID-19.

In their letter, Satish Maharaj, MD, of the James Graham Brown Cancer Center in Louisville, Kentucky, and colleagues described the case of a 69-year-old African American female patient with a history of immune thrombocytopenic purpura (TTP). She was first diagnosed in 2003 and received multiple treatments, including fondaparinux.

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In 2020, she was treated for TTP relapse and tested negative for COVID-19 with no symptoms of the disease. She responded to initial treatment but then began to decline and relapsed 5 weeks later. She was treated with plasmapheresis and steroids but was readmitted 3 weeks later. Her ADAMTS13 level was 2.1% at this readmission. After further treatment she asked to be discharged but returned 2 days later with acute hypoxic respiratory failure and tested positive for COVID-19.

ADAMTS13 activity was at 2.9% and her VWF antigen and Factor VIII activity were elevated, but her platelet count increased with COVID-19 treatment. However, she continued to test positive for COVID-19, was intubated 2 weeks after diagnosis, and died 6 weeks after diagnosis.

The authors noted that in this case and other studies, the VWF-ADAMTS13 axis seems to have a role in thrombotic disease with COVID-19. However, the studies did not explain in vivo hematologic effects of COVID-19. The authors suspected that COVID-19 affects several pathways to interact with the axis to modify the TTP/thrombotic microangiopathy (TMA) response.

“These interactions mitigate some effects that would lead to platelet consumption and result in fulminant TMA, but still drive a hypercoagulable state,” the authors concluded. Future studies should define how COVID-19 leads to hypercoagulability.


Maharaj S, Xue R, Rojan A. Thrombotic thrombocytopenic purpura (TTP) response following COVID-19 infection: implications for the ADAMTS13-von Willebrand factor axis. J Thromb Haemost. Published online December 31, 2020.  doi:10.1111/jth.15230