Partial Thromboplastin Time (PTT)
|Why is this test done?||This test is part of the analysis of the coagulation process. It is used as part of standard heparin treatment monitoring.|
|How to prepare:||
|Target Values :||
|Associated Tests:||Other tests are often done at the same time, for example platelet count , prothrombin time , and fibrinogen assay.|
Usually the blood is fluid and circulates in the vessels. If a vessel is damaged, it is important that the blood does not leak through the damaged area. To limit blood loss, a series of complex processes are activated. This is called coagulation.
Coagulation includes a cascade of enzymatic reactions involving coagulation factors, platelets, damaged wall cells, other blood protein, etc. Coagulation factors are assigned a number ranging from I to XIII. Each factor exists under an inactive and an activated form. Coagulation involves two pathways, one intrinsic the other extrinsic, which end in a final common pathway.
Coagulation is a normal and essential process. Various situations can lead to abnormal coagulation. Excessive coagulation increases the risk of thrombosis, while reduced coagulation can lead to haemorrhage.
Several tests can be done to assess coagulation. The partial thromboplastin time is a test used to evaluate the intrinsic pathway. It measures the time for a fibrin clot to form under certain conditions.
What does an abnormal test result mean?
If the result is too high
A deficiency in vitamin K or other proteins required for coagulation (called coagulation factors) can prolong the coagulation time. It can also be caused by liver problems, leukemia and von Willebrand disease. Heparin therapy prolongs the partial thromboplastin time.
If the result is too low
The partial thromboplastin time can be shorter in advanced cancer.
What you need to know before the test
Before going for blood tests, a procedure or other exam, it is best to always bring a list of all the drugs you take (prescription, OTC and natural health products). Unless told otherwise, you should take your medication as usual on the day of the test. When in doubt, ask your pharmacist for more information.
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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.