In Factor V Leiden, which coagulation factor remains active longer due to resistance to activated protein C?

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Multiple Choice

In Factor V Leiden, which coagulation factor remains active longer due to resistance to activated protein C?

Factor V Leiden causes resistance to activated protein C, which normally inactivates Factor Va. Because Factor Va is no longer efficiently cleaved, it remains active longer and continues to work with Factor Xa to convert prothrombin to thrombin. This boosts thrombin generation and tilts the balance toward clot formation. The key point is that the prolonged activity is of the activated form of Factor V (Factor Va), not Factor IIa or Prothrombin, and not Factor VIIIa, which is governed by APC inactivation in a different way.

Factor V Leiden causes resistance to activated protein C, which normally inactivates Factor Va. Because Factor Va is no longer efficiently cleaved, it remains active longer and continues to work with Factor Xa to convert prothrombin to thrombin. This boosts thrombin generation and tilts the balance toward clot formation. The key point is that the prolonged activity is of the activated form of Factor V (Factor Va), not Factor IIa or Prothrombin, and not Factor VIIIa, which is governed by APC inactivation in a different way.

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