Activated protein C resistance
Activated Protein C Resistance (APCR) is a hemostatic disorder characterized by a reduced response to the anticoagulant actions of activated protein C (APC), leading to an increased risk of venous thromboembolism (VTE). This condition is significant in the field of hematology and thrombosis, as it underlines a crucial aspect of the coagulation cascade and its regulation.
Etiology[edit | edit source]
The most common cause of activated protein C resistance is a point mutation in the factor V gene, known as Factor V Leiden. This mutation results in a variant of factor V that cannot be efficiently inactivated by APC. Other less common causes include acquired conditions such as antiphospholipid syndrome, certain medications, and some malignancies.
Pathophysiology[edit | edit source]
Under normal circumstances, activated protein C functions as a natural anticoagulant by inactivating factors Va and VIIIa, thus downregulating the coagulation cascade. In individuals with APCR, the efficiency of APC in inactivating factor Va is significantly reduced, leading to a prothrombotic state. This imbalance increases the risk of developing venous thrombosis, including deep vein thrombosis (DVT) and pulmonary embolism (PE).
Clinical Presentation[edit | edit source]
Patients with activated protein C resistance may present with recurrent venous thromboembolism at a young age, often without traditional risk factors. Family history of VTE may also be present, indicating a hereditary predisposition.
Diagnosis[edit | edit source]
The diagnosis of APCR involves a combination of clinical assessment and laboratory testing. The APC resistance assay, typically performed using a coagulometer, is the standard diagnostic test. Genetic testing for the Factor V Leiden mutation may also be conducted, especially in individuals with a family history of APCR or unexplained VTE.
Management[edit | edit source]
Management of APCR focuses on the prevention and treatment of venous thromboembolism. Anticoagulant therapy, such as warfarin or direct oral anticoagulants (DOACs), is the cornerstone of treatment. In individuals with a history of VTE, long-term anticoagulation may be recommended. Lifestyle modifications and avoidance of risk factors for thrombosis are also important aspects of management.
Prognosis[edit | edit source]
With appropriate management, individuals with activated protein C resistance can have a good prognosis. However, the risk of recurrent VTE remains, necessitating ongoing vigilance and possibly long-term anticoagulation therapy.
Epidemiology[edit | edit source]
Activated protein C resistance is the most common hereditary thrombophilia in Caucasians, with the Factor V Leiden mutation present in 3-8% of the population. The prevalence varies widely among different ethnic groups.
See Also[edit | edit source]
- Factor V Leiden
- Venous thromboembolism
- Deep vein thrombosis
- Pulmonary embolism
- Anticoagulant
- Hematology
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Credits:Most images are courtesy of Wikimedia commons, and templates Wikipedia, licensed under CC BY SA or similar.Contributors: Prab R. Tumpati, MD