hypercoagulability

Hypercoagulability, or thrombophilia, refers to an increased tendency to form blood clots. It can be inherited or acquired and results from an imbalance in the coagulation system that favors clot formation. Mechanisms include excess procoagulant activity, deficiency of endogenous anticoagulant proteins, impaired fibrinolysis, or endothelial dysfunction, often in combination with provoking factors such as illness or immobility.

Inherited forms include genetic mutations and enzyme deficiencies that raise clotting risk. Common examples are Factor V Leiden and prothrombin G20210A mutations, as well as deficiencies of protein C, protein S, or antithrombin. Less common inherited conditions also contribute. Acquired causes include antiphospholipid syndrome, cancer-associated thrombosis, prolonged immobilization, pregnancy and the postpartum period, use of estrogen-containing medications, obesity, smoking, inflammatory states, and nephrotic syndrome.

The most frequent clinical manifestations are venous thromboembolism, including deep vein thrombosis and pulmonary embolism. Arterial thrombosis can occur but is less typical. Diagnosis involves assessment of personal and family history, with laboratory testing for inherited and acquired thrombophilias in selected patients. Tests may include Factor V Leiden, prothrombin G20210A, protein C and S activity, antithrombin levels, and antiphospholipid antibodies, alongside evaluation for an active thrombus when indicated.

Management focuses on treating acute clots with anticoagulation and reducing recurrence risk. This may involve short- or long-term anticoagulation, with drug choice guided by the clinical context (for example, pregnancy or cancer). Risk factor modification and avoidance of unnecessary estrogen therapy are also important.