Prothrombin time

Prothrombin time is a test for synthetic function of liver. The clotting factors involved with the Prothrombin time are factor I, II, V, VII and X. All are produced by liver and for synthesis of factor II, VII, IX and X vitamin K is needed. Prolonged Prothrombin time indicates the deficiency of concerned clotting factors due to hepatic dysfunction or vitamin K deficiency. In hepatic dysfunction Prothrombin time is found prolonged even 18-20 hours after giving vitamin K injection.

Half life of albumin is about 20 days and that of Prothrombin is hours to days, so Prothrombin time rather than serum albumin or total protein is more sensitive and early marker of the impaired synthetic function of liver.