People with bleeding disorders undergo many blood tests throughout their lives to diagnose and manage their condition: complete blood counts, PT and aPTT tests, fibrinogen tests, clotting factor assays, inhibitor tests, and more.
You might have questions, however, about a blood test called D-dimer, which looks at the other side of the blood clotting process: how clots break down. Here’s a guide to the D-dimer test, including what it has to do with hemophilia, von Willebrand disease, and other bleeding disorders.
What Is D-Dimer?
D-dimer is a part of a protein that is created when a clot breaks down, and it’s usually only found in the body during the clot-dissolving process. D-dimer is also called fragment D-dimer or fibrin degradation fragment.
What Does the D-Dimer Test Measure?
This test isn’t part of routine care. It is normally given in emergency situations when providers think you have a serious blood clotting condition, such as deep vein thrombosis (DVT; a blood clot that forms in the deep veins of the arms or legs), pulmonary embolism (PE; a clot that forms in the lungs), or stroke (often caused by a blood clot in the brain). PE is a complication of DVT and can be life-threatening, and the dangers of stroke are well known.
The D-dimer test measures the amount of D-dimer in the blood, which indicates whether there is an abnormally high amount of clot formation in the body. For people with clotting disorders, the test is also used to see how well treatments are working.
Clotting conditions are rare among people with bleeding disorders, but they can be a side effect of factor treatment that should be examined.
For example, the National Bleeding Disorders Foundation’s Medical and Scientific Advisory Council recommends that the D-dimer test be included in laboratory monitoring of people receiving emicizumab (an antibody-based prophylactic medication that mimics the action of factor VIII) and the bypassing agent activated prothrombin complex concentrate (aPCC) for breakthrough bleeding.
What Levels Are Normal or Abnormal? Reference Ranges for Tests
Because of an inability to form clots normally, people with bleeding disorders tend to have low levels of D-dimer.
A negative or normal result means that your body isn’t forming too many clots, which may rule out concerns about serious clotting problems.
An elevated result means you could have a clotting disorder — or abnormally high clotting because of bleeding disorders treatment — and more testing is needed to further investigate your situation.
Besides those with clotting disorders, high D-dimer levels can also be found in people who are pregnant or older than 80 or have heart disease, liver disease, rheumatoid arthritis, an autoimmune disorder, trauma, an infection, or a recent surgery.
There is no standard measurement range for the D-timer test. Doctors will consider the test results along with other factors in your care.