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Uncovering the mystery of D-dimer: How to use it to eliminate the risk of thrombosis?
D-dimer, a term that may be relatively unfamiliar to many people, actually plays an important role in medical diagnosis. It is a small protein fragment that appears in the blood and is produced when blood clots are dissolved by fibrinolysis. The D-dimer test, which has been widely used since the 1990s, has become indispensable especially in the diagnosis of patients with suspected thrombotic disorders.
The importance of D-dimer concentration is that a negative result almost completely excludes the risk of thrombosis.
D-dimer is mainly used to exclude the possibility of deep vein thrombosis (DVT) and pulmonary embolism (PE). When these diseases are clinically suspected, doctors often choose to perform this test. Specifically, D-dimer testing relies on the binding of antibodies to specific sites on D-dimer fragments, and different detection kits are used to quantify this binding.
Basic principles of D-dimer
Blood coagulation, or thrombosis, occurs when various proteins in the coagulation cascade are activated. This process may be due to exposure to collagen due to vascular damage (intrinsic pathway), or tissue activating factors that promote the activation of factor VII (extrinsic pathway). Both eventually lead to the production of thrombin, an enzyme that converts soluble fibrinogen into fibrin and polymerizes it into a gel-like structure.
D-dimer consists of two D fragments. When fibrin is fully digested, D-dimer will be displayed in the plasma.
The half-life of D-dimer is about 6 to 8 hours. Under normal circumstances, D-dimer does not exist in the plasma of healthy people unless the coagulation system is activated or a condition similar to thrombus or disseminated intravascular coagulation occurs. Condition.
Clinical use and indicators
The use of the D-dimer test is based on the clinician's suspicion of DVT, PE, or disseminated intravascular coagulation (DIC). These diseases are usually judged based on a certain scoring system, such as the famous Wells score.
For low- to moderate-probability cases, a negative D-dimer result almost excludes thrombotic disease, thereby avoiding further imaging.
If the D-dimer test result is positive, then further tests, such as an ultrasound of the leg veins or a lung scan, are needed to confirm whether a blood clot is actually present. This also depends on the specific clinical situation. The doctor can decide whether to initiate anticoagulation therapy immediately based on the results.
Explanation and reference range of D-dimer
The reference range of D-dimer increases with age, so for patients over 50 years old, the indicator of "age × 10 μg/L" may be used as the basis for judgment. This approach can effectively reduce the false positive rate.
For hospitalized patients, the sensitivity of D-dimer testing can reach 93% to 95%, but false positives may occur in some cases due to various factors.
These false positive results may be related to factors such as liver disease, high rheumatoid arthritis concentrations, inflammation, or immediate surgery. False negative results may be caused by improper testing time or the influence of anticoagulants. Because of this, proper sample collection and test execution are critical.
Historical background of D-dimer
The discovery of D-dimer can be traced back to the 1970s, and it was widely used in diagnosis in the 1990s and remains an important clinical tool today. With the deepening of medical research, D-dimer detection methods continue to improve, and as the understanding of its role deepens, its application becomes more widespread.
To sum up, D-dimer detection is an efficient and relatively safe inspection process in modern medicine, which can effectively help eliminate the risk of thrombosis. However, when facing this examination result, can we still have a deeper understanding of the meaning and causative factors behind the body?
