Which is likely to be increased in vitamin K deficiency: March 2004

Ans. B i.e. PT Prothrombin time (PT) PT and its derived measures of prothrombin ratio (PR) and international normalized ratio (INR) are measures of the extrinsic pathway of coagulation. This test is also called "ProTime INR" and "PT/ INR". They are used to determine the clotting tendency of blood, in the measure of warfarin dosage, liver damage, and vitamin K status. PT measures factors I (fibrinogen), II (thrombin), V, VII, and X. It is used in conjunction with the activated paial thromboplastin time (aPTT) which measures the intrinsic pathway.