D-Dimer Normal Range

What is D-dimer?

Fibrinolysis can lead to the degradation of a blood clot resulting in the formation of a fibrin in the blood clot. This tiny protein fragment is called D-dimer. It is so called because of the presence of two D portions of the protein fibrinogen that are cross linked.

The D-dimer molecule was discovered in the 1970s, but it was not until the 1990s that it was put into medical diagnosis and use. A blood test is used to determine the concentration of D-dimer in the blood

Thrombosis is a condition that affects the ability of the blood to form clots and a D-dimer test is done to diagnose the presence of the condition.

The importance of D-dimer

Under normal circumstances the blood plasma does not consist of the D-miner fragments. However, in cases where there is activation of the coagulation system such as disseminated intra-vascular coagulation or thrombosis there may be presence of d-dimer in the blood plasma.

The strapping of a monoclonal antibody to the D-dimer molecule is essential to the evaluation of D-dimer. Thus we can conclude that the levels of D-dimer can essentially indicate the presence of blood clots in the lungs or pulmonary embolism or conditions such as deep vein thrombosis.

The checking of D-dimer range, normal or otherwise, can help in allaying and confirming suspicions about individuals who may be suffering from blood clot conditions or from scattered intra-vascular coagulation

D-dimer normal range

The normal range for D-dimer is approximately 0.5 mg/l of blood or 500 mg/ml of blood.

Testing of d-dimer range is usually not done when suspicions of individuals who have symptoms of scattered intra-vascular coagulation have been confirmed and have been diagnosed to be suffering from the condition. In such cases, treatment starts straightway with anticoagulant therapy. Doctors also conduct further tests to determine the presence of pulmonary embolism.

When there is a pretest probability of low D-dimer or when a patient has a low score, then a D-dimer test with negative score will definitely rule out the presence of thromboembolism. This is because the characteristics of the specific test that are being employed in that particular clinical setting influences the degree to which d-dimer values diminish the possibility of thrombotic disease.

A higher than normal test result of D-dimer values necessitates a number of further tests to determine the probability and possibility of thrombus. Some of these tests may include a CAT scan, a lung scintigraphy or an ultrasound of the veins in the legs. However, to prevent any more damage to the body an anticoagulant therapy is initiated long before the above test results are confirmed.

Disparities in the D-dimer test results

D-dimer blood tests can be carried out with a number of medical tools and kits that have a high range of sensitivity. Moreover, more than half of such tests are particularly sensitive to the diagnosis of thrombotic diseases.

However, in certain cases, the D-dimer tests results may vary in accuracy of diagnosis.  Some test results may mislead as to the range of D-dimer with a false positive test result. This can be the case in individuals who have conditions such as liver abnormalities, presence of benign or malignant tumors, pregnancy as well as extreme cases of injuries that result in severe blood loss and excessive blood clotting. Individuals who are at an increased age or who have recently undergone surgery may also be susceptible to false positive results.

A false negative test result may result from a test that is conducted too early after affliction with the condition or in cases wherein the testing for thrombus is held up by several days.