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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.

What abnormal results mean:

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

  • Reviewed last on: 3/9/2007
  • Mark Levin, MD, Hematologist and Oncologist, Newark, NJ. Review provided by VeriMed Healthcare Network.

References

Ferri FF. Ferri’s Clinical Advisor: Instant Diagnosis and Treatment. 2005 ed. St. Louis, Mo: Mosby; 2005:1365.

Hoffman R, Benz EJ, Shattil SS, et al. Hematology: Basic Principles and Practice. 4th ed. Orlando, Fl: Churchill Livingstone; 2005:2004-2005.