Secondary fibrinolytic enhancement

Introduction The fibrinolytic system is the most important anticoagulant system in the human body. During the dissolution process, thrombin hydrolyzes fibrin, releasing soluble fibrin monomer and forming a stable cross-linked fibrin under the action of factor xIIIa. In the late stage of disseminated intravascular coagulation, the fibrinolytic system is activated due to intravascular coagulation, resulting in secondary fibrinolysis, and the bleeding symptoms are more obvious.

Cause

Secondary fibrinolysis, such as thrombotic disease, DIC, etc., due to the enhanced blood coagulation mechanism in the early stage of the disease, fibrin is produced in large quantities, which in turn causes fibrinolysis. In the late stage of disseminated intravascular coagulation, the fibrinolytic system is activated due to intravascular coagulation, resulting in secondary fibrinolysis, and the bleeding symptoms are more obvious.

an examination

Related inspection

Determination of plasma tissue plasminogen by plasma plasminogen activator antigen assay by plasminogen

1. When thrombin time prolongs fibrinogen significantly or fibrinogen (original) degradation products (FDP) increase, thrombin time is prolonged, but the results of the assay can be affected by heparin treatment. The use of continuous thrombin time is a more sensitive indicator for the diagnosis of FDP.

2. Plasma venom coagulation time The thrombin time was determined by replacing the thrombin with an enzyme (Reptilase) extracted from snake venom. When the FDP increases, the clotting time is prolonged, and the advantage of the method is that it is not affected by heparin.

3. Examination of fibrin degradation products There are only traces of FDP in normal human serum. If the FDP is significantly increased, it means that fibrinolysis is hyperactive, which indirectly reflects DIC. There are many methods for determination, including immunoassay Fi test (ie latex particle agglutination test, normal titer <1:8), FDP flocculation test, radioimmunoassay method, staphylococcal sputum test (normal FDP value is 0.57±0.1 g /dl, DIC can be as high as 60g/dl), citrate is better than red blood cell indirect hemagglutination inhibition test (normal serum FDP value <10g/dl, DIC more than 20g/dl), enzyme membrane immunoadsorption technology. If the FDP increases, it indicates the possibility of acute DIC.

4. Plasma protamine co-coagulation test (abbreviated 3P test) and ethanol gel test This is a test that reflects the soluble fibrin complex in plasma. When intravascularly coagulates, FDP binds to fibrin monomers to form a soluble complex that cannot be coagulated by thrombin. Protamine can separate the complex and re-precipitate the fibrin monomer. As a result, self-polymerization of fibrin monomer and FDP occurs, forming a macroscopic flocculent precipitate called a coagulation test. The principle of ethanol glue test is the same as that of 3P test. According to domestic data, the positive rate of 3P test is 72.6-88.2%, and the positive rate of ethanol glue is low. Both methods can have false positive or false negative results. In contrast, the ethanol gel test is poorly sensitive, but more reliable; while the 3P specificity is poor, and there are many false positives. If the molecular weight of the FDP split is small, the 3P test can also be negative. It is better to compare the two with each other and the meaning is even greater.

5. Euglobulin lysis time euglobulin is a protein component of plasma precipitated in an acidic environment, containing fibrinogen, fibrinogen and its activin, but no fibrinolytic inhibitor, can be used to determine fibrin Whether the lysogen activator is increased. The normal value should be more than 2 hours. If dissolved within 2 hours, it means that fibrinolysis is hyperactive. When fibrinolysis increases, plasminogen decreases, plasmin increases, and euglobulin is accelerated by a large amount of plasmin. The positive rate of domestic data reports is 25 to 42.9%.

Differential diagnosis

Plasma D-dimer This is a specific product after fibrin degradation. Determination of plasma D-dimer can determine whether fibrin has been formed, thus providing an important basis for the identification of primary and secondary fibrinolysis.

Qualitative test: Negative quantitative test: <400 g / L. In primary fibrinolysis, fibrinogen is degraded before it is converted to fibrin in large quantities, D-dimer is negative or not elevated; secondary fibrinolysis, such as thrombotic disease, DIC Etc., due to the enhanced blood coagulation mechanism in the pre-disease, fibrin is produced in large quantities, which in turn causes fibrinolysis, so D-dimer is positive or significantly elevated. Generally, fasting venous blood is collected in a quiet state.

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