Causes of thrombosis

Causes of the origin

Thrombosis is a vascular disease in which blood clots (thrombi) form in the blood vessels. The deep veins of the legs or pelvis (phlebothrombosis) are often affected. However, there are also arterial thromboses or thrombosis of the venous sinuses of the brain.

The focus of this article will be on the development and causes of deep vein thrombosis. There are various causes and risk factors that contribute to the development of thrombosis. A distinction is made between genetic predispositions and clotting tendencies and external factors.

The development of a thrombus and the causative factors, i.e. the pathogenesis, are very well described in the Virchow Triad. This model explains the mechanisms underlying thrombus formation. It is often more important for patients to understand which clinical pictures, risk factors and behavioral patterns favor the development of thrombosis.

Hereditary thrombophilia is an important aspect in the development of thrombosis. These are congenital disorders of the coagulation system that lead to increased coagulability of the blood, as a result of which thrombosis is highly likely to develop. People with a congenital thrombophilia have an up to 80 times higher risk of suffering a thrombosis than people who do not have this tendency to clot.

In addition, if other risk factors are present or if several thrombophilia patients are present at the same time, the risk is even higher. These congenital thrombophilia include APC resistance, protein C, protein S and antithrombin deficiency and prothrombin mutation. Particularly in the case of very frequent thromboses or a very young age of the disease, a detailed special thrombophilia diagnosis is recommended.

Other causes of thrombosis are advanced age (over 60) and cancer. Pregnant women and women in childbed also have an increased risk. This is partly due to increasing immobilization and partly to hormonal causes.

During childbirth, an increased amount of coagulation-active substances are released. Prolonged immobilization of the extremities, for example during a long bus journey, bedriddenness or a paralyzed extremity, is also a massive risk factor for the development of thrombosis. This has to do with the fact that the blood flow is slowed during immobilization and this promotes clotting.

This is how blood clots develop. Another risk factor is estrogen therapy, e.g. as part of menopausal replacement treatment or when taking oral contraceptives. However, it is important to differentiate here that this is not a monocausal connection but rather a multifactorial event.

This means that thrombosis does not occur solely as a result of taking medication but rather as a result of many mutually potentiating factors. Overweight and nicotine abuse also promote thrombosis. Another very important risk factor is the antiphospholipid syndrome.

This disease occurs either without a recognizable cause (primary) or in the context of an underlying disease such as cancer, HIV, lupus erythematosus and rheumatism (secondary) and leads to many thromboses at various sites. Antibodies are responsible for the formation of the clots. In women, frequent miscarriages are typical in the medical history.