Unexplained increased D-dimer levels

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.

Is an unexplained increase in the D-dimer level an indication to test for thrombophilia? Is it an indication to introduce antithrombotic prophylaxis?

D-dimer testing is extremely problematic. I was involved in some of the studies that led to the widespread implementation of D-dimer, and it’s probably the test that I regret most having worked on, because D-dimer is misused in so many circumstances.

The direct answer to this question is absolutely not. There are so many different causes of an elevated D-dimer. It’s extraordinarily nonspecific. It by itself is never an indication for anticoagulant therapy.

In fact, you should not be testing D-dimer chronically in patients with venous thromboembolism. There’s absolutely no evidence that that influences your decisions with respect to management. It’s certainly not an indication for thrombophilia testing.

It really is a test which, if we could make it go away, I would make it go away, because it leads to so many questions that are completely unnecessary.