Which treatment would NOT restore a prolonged prothrombin time (PT) to the normal range?

Which treatment would NOT restore a prolonged prothrombin time (PT) to the normal range?

• A. Recombinant factor VIII
• B. Vitamin K
• C. Fresh frozen plasma
• D. Stopping warfarin

Answer: (A)

Prothrombin time reflects the extrinsic and common coagulation pathways, mainly depending on factor VII and the vitamin K–dependent factors II, VII, IX, X. When PT is prolonged because of warfarin, the goal is to restore those extrinsic pathway factors. Stopping warfarin allows natural recovery of vitamin K–dependent factors over time. Vitamin K helps the liver re-synthesize II, VII, IX, and X, shortening the PT. Fresh frozen plasma provides immediate replenishment of these factors, rapidly normalizing PT. Recombinant factor VIII, however, targets the intrinsic pathway and replenishes factor VIII. It does not affect the extrinsic pathway factors, so it would not shorten a prolonged PT. That’s why this option would not restore PT to normal, while the others would.

Prothrombin time reflects the extrinsic and common coagulation pathways, mainly depending on factor VII and the vitamin K–dependent factors II, VII, IX, X. When PT is prolonged because of warfarin, the goal is to restore those extrinsic pathway factors. Stopping warfarin allows natural recovery of vitamin K–dependent factors over time. Vitamin K helps the liver re-synthesize II, VII, IX, and X, shortening the PT. Fresh frozen plasma provides immediate replenishment of these factors, rapidly normalizing PT.

Recombinant factor VIII, however, targets the intrinsic pathway and replenishes factor VIII. It does not affect the extrinsic pathway factors, so it would not shorten a prolonged PT. That’s why this option would not restore PT to normal, while the others would.