heparin-induced thrombocytopenia
Introduction
Introduction to heparin-induced thrombocytopenia Heparin-induced thrombocytopenia, heparin-induced thrombocytopenia is not clearly related to the dose of heparin, the route of injection and the history of previous heparin exposure, but is related to the source of heparin preparations. . basic knowledge Sickness ratio: 0.01%-0.02% Susceptible people: no specific population Mode of infection: non-infectious Complications: thrombocytopenia leukemia
Cause
Causes of heparin-induced thrombocytopenia
(1) Causes of the disease
Various forms of heparin can induce thrombocytopenia. Experimental studies have shown that high molecular weight heparin is more likely to interact with platelets, leading to thrombocytopenia, which occurs in clinically observed thrombocytopenia in patients treated with low molecular weight heparin. The results are lower at the same rate.
(two) pathogenesis
Heparin-induced thrombocytopenia may be related to the immune mechanism. Some patients may have a specific antibody IgG, which can bind to heparin-PF4 (platelet factor 4) complex, also known as "heparin-binding cationic protein". Secreted by platelet alpha granules, then bound to the surface of platelets and endothelial cells, secreted by platelet alpha granules, then bound to the surface of platelets and endothelial cells, antibody-heparin-PF4 forms a 3 molecule complex, and then with the Fc IIa on the platelet surface Receptor binding, immune complexes can activate platelets, produce procoagulant substances, is a possible mechanism of heparin-induced thrombocytopenia with thrombotic complications, and thrombocytopenia caused by other drugs generally have no thrombotic complications, can be used as identification .
Immune complexes activate platelets by cross-linking with FcR IIa molecules on the surface of platelets. The His/Arg polymorphism at position 131 of the FcR IIa amino acid chain can affect its ability to bind to IgG, which can be used as a predictor to predict heparin. Individual risk of induced thrombocytopenia.
Prevention
Heparin-induced thrombocytopenia prevention
Fully recognizing the potential for heparin therapy to induce thrombocytopenia, frequent review of platelet counts is the primary preventive measure, and the use of low molecular weight heparin can reduce the incidence of this disease.
Complication
Heparin-induced thrombocytopenia complications Complications thrombocytopenia leukemia
Aplastic disorder
Many patients with secondary thrombocytopenia are caused by other diseases, bone marrow hyperplasia is low, and thrombocytopenia can occur first, followed by low proliferation of erythroid and granulocyte lines.
2. Myelodysplastic abnormalities
Radical thrombocytopenia disease also needs to trigger the specific cause of secondary thrombocytopenia in order to fundamentally solve the secondary thrombocytopenia disease, the first megakaryocyte reduction caused by thrombocytopenia, followed by red blood cell line, granulocyte-single Nuclear cell line morbid hematopoiesis.
3. Bone marrow occupying lesions
People should be aware of the key causes of secondary thrombocytopenia disease in order to make better preventive measures. Some malignant tumors invade the bone marrow to reduce megakaryocyte production and inhibit its maturation, showing thrombocytopenia, such as leukemia, malignant lymphoma, cancer metastasis. Wait.
Symptom
Heparin-induced thrombocytopenia symptoms common symptoms thrombocytopenia intravascular coagulation microthrombus abnormal uterine bleeding
According to the clinical course of thrombocytopenia induced by heparin therapy, it can be divided into temporary thrombocytopenia and persistent thrombocytopenia.
Temporary thrombocytopenia
Most of the platelets are reduced immediately after the start of heparin treatment, but generally not less than 50 × 109 / L, may be related to the induced aggregation of platelets by heparin, which can cause temporary aggregation of platelets and platelet adhesion High, platelets are blocked in the blood vessels, resulting in transient thrombocytopenia.
2. Persistent thrombocytopenia
Less common than the former, usually occurs 5 to 8 days after heparin treatment, if the patient has been treated with heparin, thrombocytopenia may occur immediately, the platelet count may be less than 50 × 109 / L, no less than 10 × 109 / L, in addition to thrombocytopenia, can be accompanied by thrombosis and disseminated intravascular coagulation, bleeding symptoms are rare, mainly manifested as thrombosis.
Examine
Heparin-induced thrombocytopenia
1. Peripheral blood: white blood cells, red blood cells, no change in platelet morphology, and decreased platelet count.
2. Bone marrow: The megakaryk system can be unchanged.
Antibodies detect heparin-dependent antiplatelet antibodies, and patients with transient thrombocytopenia do not have heparin-dependent antiplatelet antibodies.
Diagnosis
Diagnosis and identification of heparin-induced thrombocytopenia
A history of drugs with heparin can be diagnosed in conjunction with laboratory tests for thrombocytopenia.
