Which test assesses vitamin K-dependent coagulation factors?

• A. II, VII, IX, X
• B. I, V, VIII, XIII
• C. II, V, IX, XII
• D. XI, XII, Fletcher, Fitzgerald

Answer: (A)

Vitamin K–dependent coagulation factors are II, VII, IX, and X. These factors require vitamin K for gamma-carboxylation to become active, and the prothrombin time (PT) test is used to assess their function because it reflects the activity of these factors in the extrinsic/common pathways. The option listing II, VII, IX, and X matches exactly the vitamin K–dependent set, making it the best choice. The other groups include factors that are not vitamin K–dependent (such as fibrinogen I, V, VIII, XIII, XII), so they don’t represent the vitamin K–dependent factors.