Prothrombin time (PT)

The normal range is 11 to 13.5 seconds ("normal" varies somewhat in different labs).

For a person on full anticoagulant therapy, the PT should be 2 to 3 times the laboratory "control" value.

Increased PT times may indicate:

• bile duct obstruction
• cirrhosis
• disseminated intravascular coagulation
• hepatitis
• malabsorption (inadequate absorption of nutrients from the intestinal tract)
• Vitamin K deficiency
• Coumadin (warfarin) therapy
• Factor VII deficiency
• Factor X deficiency
• Factor II (prothrombin) deficiency
• Factor V deficiency
• Factor I (fibrinogen) deficiency

This test may be performed under many conditions in the evaluation of a wide variety of disorders.

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