APC resistance

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Classification according to ICD-10
D68.5 Primary thrombophilia; Resistance to activated protein C
ICD-10 online (WHO version 2019)

APC resistance (activated protein C resistance) describes the resistance of the activated factor V (FVa) of the coagulation cascade to activated protein C (APC). It is a blood clotting disorder ( thrombophilia ), which is characterized by an increased incidence of thromboses (venous blood clots).

The most common cause (> 95%) is a genetically determined structural defect that changes the blood coagulation factor V - the so-called Factor V Leiden mutation ( Leiden stands for the Dutch city in which the mutation was first described). In the coagulation cascade, protein C, together with the cofactor protein S , normally prevents an excessive coagulation reaction. Due to the mutation in the “docking point” for the activated protein C, the activated coagulation factor V is broken down much more poorly, so there is an increased tendency to thrombosis, a thrombophilia. A deficiency in coagulation factor V, which is associated with an increased risk of bleeding, must be distinguished from this.

Especially in younger patients (20 to 40 years of age), APC resistance is responsible for up to 30% of all thromboses. If hormonal contraceptives are also taken, the risk of thrombosis increases considerably in heterozygous women, and up to 200 times in homozygous women.

There is no possibility of causal therapy for APC resistance. Depending on the risk and accompanying circumstances (obesity, surgery, long flight, bed restraint), thrombosis prophylaxis, e.g. B. with heparin syringes, be indicated. During pregnancy, due to the increased risk of thrombosis in women with additional genetic defects in blood clotting, low molecular weight heparin is used because of the fewer side effects. The genetic defect is passed on from the parents to children of both sexes. Mutation of factor V occurs in children of both sexes . Anticoagulation with z. B. is suitable as therapy after a thrombosis or pulmonary embolism . B. heparins , phenprocoumon or approved direct oral anticoagulants .

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