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Partial thromboplastin time (PTT) - Results

Alternative Names

APTT; PTT; Activated partial thromboplastin time

Normal Values:

The normal value will vary between laboratories. In general, clotting should occur between 25 to 35 seconds. If the person is taking blood thinners, clotting takes up to two and a half times longer.

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:

An abnormal (too long) PTT result may be due to:

Cirrhosis
Disseminated intravascular coagulation (DIC)
Factor XII deficiency
Hemophilia A
Hemophilia B
Hypofibrinogenemia
Lupus anticoagulants
Malabsorption
Vitamin K deficiency
Von Willebrand's disease

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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