Prothrombin (PT)

Prothrombin, also called Factor II, is a vitamin K dependant coagulation factor, glycoprotein of about 72 kD, synthesized in the liver. Prothrombin is usually present at about 100micrograms/mililiter in plasma.

Prothrombin is a zymogen converted to thrombin by the action of factor Xa and factor V in the presence of phospholipids and calcium. Meizothrombin is an intermediate formed during this conversion of prothrombin, which is active toward synthetic specific peptide substrate.