Persistently elevated D-dimer levels after COVID-19

Mark Crowther, MD, MSc, is a professor of medicine, chair of the Department of Medicine, and Leo Pharma Chair in Thromboembolism Research at McMaster University.

How to interpret persistently elevated D-dimer levels in patients with a history of COVID-19? How to proceed in such cases?

This is an excellent question. What we know about coronavirus disease 2019 (COVID-19) is that we don’t know a lot about COVID-19. There is a group of patients who seem to have ongoing, persistent, and otherwise unexplained activation of their coagulation systems after COVID-19.

I would say that much more research is required in this area. I looked, in preparation for this question, to see if there was any recent evidence to suggest what we should do with these patients, and there is no good quality evidence. I would be very uncomfortable saying that this person has an elevated D-dimer test, had recent COVID-19, and that would indicate that they should receive some specific form of therapy. It would indicate to me that we should be looking carefully in that patient to see if we can find an explanation for this. For example, do they have an undiagnosed malignancy or infection of a different sort? And then I would watch them closely to see what happened to them over time.

However, an isolated elevated D-dimer by itself, in my opinion, is not an indication to do anything specific.