In liver disease, which coagulation factor deficiency most contributes to prolonged PT?

• A. Factor VII
• B. Factor II
• C. Factor V
• D. Factor X

Answer: (A)

PT reflects the extrinsic pathway, which hinges on Factor VII. In liver disease, the liver’s ability to synthesize clotting factors drops, but Factor VII has the shortest half-life among the vitamin K–dependent factors. Because it falls first, the extrinsic pathway slows and PT becomes prolonged earlier than changes in factors with longer half-lives (like II and X). Factor V isn’t vitamin K–dependent and its decrease is less specifically tied to PT prolongation. So the most likely reason for a prolonged PT in liver disease is a deficiency of Factor VII.