Increasing vitamin K intake will decrease which liver function test value?

Increasing vitamin K intake will decrease which liver function test value?

• A. Alkaline Phosphatase (ALP)
• B. Aspartate Aminotransferase (AST)
• C. Prothrombin Time (PT)
• D. Alanine Aminotransferase (ALT)

Answer: (C)

Vitamin K is required for gamma-carboxylation and activation of the vitamin K–dependent clotting factors II, VII, IX, and X. When intake is increased, these factors become functionally active again, improving the clotting cascade and shortening the prothrombin time, which specifically measures the extrinsic pathway and is very sensitive to vitamin K status (factor VII has a short half-life, making PT a quick responder). The other liver tests reflect hepatocellular injury or biliary flow (AST, ALT, ALP) and are not directly improved by vitamin K repletion, so they do not decrease with increased vitamin K.

Vitamin K is required for gamma-carboxylation and activation of the vitamin K–dependent clotting factors II, VII, IX, and X. When intake is increased, these factors become functionally active again, improving the clotting cascade and shortening the prothrombin time, which specifically measures the extrinsic pathway and is very sensitive to vitamin K status (factor VII has a short half-life, making PT a quick responder). The other liver tests reflect hepatocellular injury or biliary flow (AST, ALT, ALP) and are not directly improved by vitamin K repletion, so they do not decrease with increased vitamin K.