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Prothrombin time (PT) - Results

Alternative Names

PT; Pro-time

Normal Values:

The normal range is 11 to 13.5 seconds. The PT result will be longer in persons who take blood thinners.

Note: Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.

What abnormal results mean:

When any of the blood clotting factors are lacking or not working properly, the PT is prolonged.

Increased PT may be due to:

Bile duct obstruction
Cirrhosis
Disseminated intravascular coagulation
Hepatitis
Liver disease
Malabsorption
Vitamin K deficiency
Coumadin (warfarin) therapy
Factor VII deficiency
Factor X deficiency
Factor II (prothrombin) deficiency
Factor V deficiency
Factor I (fibrinogen) deficiency

Reviewed last on: 2/21/2009
David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

References

Schafer AI. Approach to the patient with bleeding and thrombosis. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 178.

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