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Partial thromboplastin time

Blood coagulation is a critical process that enables blood to form clots and stop bleeding. This complex process ensures that bleeding is controlled while enabling wounds to heal.

Under certain circumstances, the process doesn't happen as expected. Excessive coagulation increases the risk of thrombosis (blood clots), while reduced coagulation increases the risk of bleeding.

What is the purpose of this test? This test is used to measure the time it takes for blood to form a clot. It is performed for several reasons, including the following:
  • To monitor certain treatments (e.g., heparin)
  • To diagnose diseases involving coagulation factors (e.g., Von Willebrand disease)
  • To assess a case of unexplained bleeding (e.g., a person experiencing frequent nosebleeds or bruises)
  • As part of a preoperative assessment
How to prepare?
  • No preparation needed.
Reference values*
  • 22 to 30 seconds
Associated tests Other tests related to blood coagulation may be performed at the same time:
How is it done? A blood sample is drawn, usually from a vein in the arm.
How long before I get the results? Results are usually ready in a day. It may take longer to receive your results.
* These values are presented for information purposes only. As different laboratories may have different target values, the lab report usually specifies the values used for the test. It should also be noted that test results must be interpreted based on factors such as age, sex, and health condition. Values outside of this range may be considered normal for some individuals.

What does an abnormal test result mean?

Partial thromboplastin time results cannot be interpreted independently. It is important to consider the results of other tests typically carried out at the same time to identify the possible cause of abnormal values.

Prolonged partial thromboplastin time

A prolonged partial thromboplastin time could be caused by the following:

  • Vitamin K deficiency
  • A coagulation factor deficiency
  • A liver issue
  • Certain types of cancer (e.g., leukemia)
  • Von Willebrand disease
  • Heparin treatment

Shortened partial thromboplastin time

A shortened partial thromboplastin time could be caused by the following:

  • Certain types of advanced cancer
  • Inflammation or trauma

What you should know before going for this test

When you go in for a blood test or any other medical exam, it's always a good idea to bring a complete list of any prescriptions, over-the-counter medications, or natural health products you're taking. Unless otherwise advised, it's best to take your medications as usual on blood test days. If in doubt, don't hesitate to talk to your healthcare professional.

© Copyright Vigilance Santé

The patient information leaflets are provided by Vigilance Santé Inc. This content is for information purposes only and does not in any manner whatsoever replace the opinion or advice of your health care professional. Always consult a health care professional before making a decision about your medication or treatment.

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