What are D Dimers?
What is the significance of very high D dimers?
D-dimer is a fibrin degradation product, a small protein fragment present in the blood after a blood clot is degraded by fibrinolysis. D-dimer concentration may be determined to diagnose thrombosis. It has become an important test performed in people with suspected thrombotic disorders, such as venous thromboembolism While a negative result practically rules out thrombosis, a positive result can indicate thrombosis but does not exclude other potential causes. Its main use, therefore, is to exclude thromboembolic disease where the probability is low.
D-dimer tests are used to help rule out the presence of an inappropriate blood clot (thrombus). Some of the conditions that the D-dimer test is used to help rule out include:
This test may be used to determine if further testing is necessary to help diagnose diseases and conditions that cause hypercoagulability, a tendency to clot inappropriately. A D-dimer level may be used to help diagnose DIC and to monitor the effectiveness of DIC treatment.
A positive D-dimer result may indicate the presence of an abnormally high level of fibrin degradation products. It indicates that there may be a significant blood clot (thrombus) formation and breakdown in the body, but it does not tell the location or cause. For example, it may be due to a venous thromboembolism (VTE) or DIC. Typically, the D-dimer level is very elevated in DIC.
However, an elevated D-dimer does not always indicate the presence of a clot because a number of other factors can cause an increased level. Elevated levels may be seen in conditions in which fibrin is formed and then broken down, such as recent surgery, trauma, infection, MI, and some cancers or conditions in which fibrin is not cleared normally, such as liver diseases Therefore, D-dimer is typically not used to rule out VTE in hospitalized patients.
DDimer has got a high sensitivity so good in excluding throbmotic phenomena however specificity is not that good. So for confirmation additional aid like scoring system or clinical suspicion has to be relied upon.
Which clinical scoring system is commonly used?
The Wells score is a number that reflects your risk of developing Deep Vein Thrombosis. DVT happens when a blood clot forms in a vein that’s deep inside your body, usually in your leg.
A score 3 or higher indicates High Risk of DVT; A score of 1 or 2 indicates Moderate Risk of DVT; A score of 0 indicates DVT is not likely.
| Symptom and risk factors | Points |
| Active cancer, or cancer that’s been treated within last six months | 1 |
| Paralyzed leg | 1 |
| Recently bedridden for more than three days or had major surgery within last four weeks | 1 |
| Tenderness near a deep vein | 1 |
| Swollen leg | 1 |
| Swollen calf with diameter that’s more than 3 centimeters larger than the other calf’s | 1 |
| Pitting edema in one leg | 1 |
| Large veins in your legs that aren’t varicose veins | 1 |
| Previously diagnosed with DVT | 1 |
|
Other diagnosis more likely |
-2 |