What coagulation test results are indicative of Vitamin K deficiency?

Vitamin K deficiency primarily affects the synthesis of several clotting factors, specifically factors II (Prothrombin), VII, IX, and X, in the liver. These factors are crucial components of the extrinsic and common coagulation pathways.

The prothrombin time (PT) is sensitive to deficiencies in the extrinsic pathway, particularly involving factor VII, which has a relatively short half-life and is one of the first factors impacted by vitamin K deficiency. As a result, in vitamin K deficiency, the PT will be prolonged.

On the other hand, the activated partial thromboplastin time (APTT) is more related to the intrinsic pathway, which involves factors like VIII, IX, XI, and XII. While APTT may also be affected, it typically remains within normal limits during early vitamin K deficiency, especially if the deficiency is not severe or if there is still sufficient factor IX.

Thus, when both the PT and APTT are elevated, as seen in this case, it signals a problem with the clotting factors affected by vitamin K, confirming the diagnosis of vitamin K deficiency. Therefore, prolonged PT alongside a normal APTT is indicative of this deficiency, reflecting the specific involvement of vitamin K-dependent factors in coag