The D-dimers blood test is at test that is conducted to detect the possibility of deep vein thrombosis or even a pulmonary embolism. D-dimer is fibrin degradation product that roams in the blood waiting to be excreted and is a result of the breakdown of blood clots in the body by an enzyme like plasmin. Clots are extremely complex from a molecular perspective. They are formed by the action of thrombin and fibrogen that create a series of D-dimer matrices around the site of an injury and further clotting factors turn this matrix of clots into a cross-linked structure giving it immense strength and sealing power. When a clot is broken down by an enzyme like plasmin, the cross-linked structure and the matrices are broken, but the D-dimer of a blood clot cannot be broken down. This results in this molecule roaming in the blood stream until it is excreted.
The test is performed to check and confirm the presence of thrombosis in the body. More importantly, it can also indicate the imminence of a pulmonary embolism as well. An embolism is the movement of a solid fragment from one part of the body to another - in this case, a solid clot; as the amount of d-dimer increases in the blood the more likely an embolism. When an embolism reaches the lungs, it can be fatal, and is called a pulmonary embolism.
The D-dimer test is done by various methods including the ELISA assay. This test is conducted by simply taking a blood sample from the patient and then analyzing the blood for the presence of the protein in the blood. The evaluated D-dimer blood test reference ranges are 0-300 nanograms/milliliter. Any value above this measurement is considered dangerous. In many instances, the test is just secondary and most doctors will start treatment with drugs like heparin and warfarin for the thrombosis. Warfarin should ideally not be used on pregnant women because it is teratogenic, and will cause severe birth defects in the child.
There is no preparation that is required to be done for the test though you must inform the person taking the blood that you might be on blood thinners or anticoagulant medication and any diseases like liver disease and rheumatoid arthritis. There are some herbs that are also able to replicate the effects of blood thinning medication.