Some patients, especially when it comes to pregnant women, are prescribed a D-dimer test. What it is? Why do we need such tests? What diseases can be diagnosed using a similar technique?
D-dimer - what is it?
The mechanism of blood coagulation is quite complex. But to summarize, it looks like this. Under the action of thrombin, fibrin is formed, which is then amenable to the action of plasmin.
This enzyme breaks down the molecules of fibrin and fibrinogen into smaller fragmentary ones.
Sometimes during the process of fibrinolysis, plasmin is not able to completely split the fibrin fiber, as a result of which D-dimers are formed - rather large structures. Thus, the analysis for the presence of D-dimers gives doctors the opportunity to evaluate the processes of blood coagulation and detect a tendency to thrombosis.
How to prepare for blood donation?
Fortunately, modern medicine has developed tests to help determine if D-Dimer is present in blood plasma. What are these analyzes? The level of this substance can be determined using methods of immunological studies of blood plasma.
Blood sampling is carried out in the morning, always on an empty stomach (you can drink only clean water). Do not smoke before donating blood. Also, do not expose the body to heavy physical exertion. A day before the procedure, it is worth excluding fatty foods from the diet, as this can affect the blood test.
D-dimer is an important marker, as it helps to track the mechanism of formation and breakdown of fibrinogen. This study is used for suspected thrombosis and DIC.
D-dimer indicators are increased: what does this mean?
Normally, the dimer level in the blood should not exceed 500 ng / ml. In most cases, an increase in this indicator indicates the presence of a blood clot. In particular, the analysis is often used to diagnose deep vein thrombosis or pulmonary embolism.
On the other hand, there are other reasons that can lead to such a violation. Risk factors include old age, since in almost every patient older than 80 years, D-dimer is increased. In addition, a similar pattern is observed in pregnant women.
In some cases, an increase in the level of this substance is associated with diseases, for example, the presence of a tumor or infection. In addition, the same result is observed with some liver lesions, in the presence of active inflammatory processes, disseminated intravascular coagulation.
Risk factors include extensive hematomas, myocardial infarction, coronary heart disease. Sometimes such results can be obtained against the background of thrombolytic therapy.
Reasons for False Negative Results
Under the influence of some factors, even with thrombosis, you can get the result, where D-dimer is normal. What are these factors that affect the accuracy of research? To begin with, it is worth noting that D-dimer - a substance that decomposes relatively quickly - six hours after its appearance in the blood, it is no longer possible to detect traces of it.
In some cases, false-negative results appear with too small blood clots. In any case, to make an accurate diagnosis, the patient undergoes several diagnostic procedures at once.