Prothrombin Time(PT)

Prothrombin Time(PT)

Normal range

      11 –16 seconds

      Indication

Control of long – term oral anticoagulant therapy with coumarins and indanedione derivatives; evaluation of liver functions( PT is the most useful test of impaired liver synthesis of prothrombin complex factors[ factor II, VII, IX, Protein C & S]; evaluation of coagulation disorders- screen for abnormality of factors involved in extrinsic pathway (factor V, VII, IX, Prothrombin, fibrinogen). Should be used with a PTT.

Prolonged by defect in

Factor I, II, V, VII and X

Prolonged in

In adequate vitamin K in diet, premature infants, newborns of vitamin K deficient mothers, poor fat absorption (obstructive jaundice, colitis, steatorrhea), severe liver damage (hepatitis, poisoning), anticoagulant drugs, familial hypoprothrombinemia.