Partial Thromboplastin Time

Partial thromboplastin time (PTT) is done to:

• Find a cause of abnormal bleeding or bruising.
• Check for low levels of blood clotting factors. The lack of some clotting factors can cause bleeding disorders such as Reference hemophilia Opens New Window.
• Check for conditions that cause clotting problems. Conditions such as antiphospholipid antibody syndrome or lupus anticoagulant syndrome develop when the immune system makes Reference antibodies Opens New Window that attack blood clotting factors. This can cause the blood to clot easily in veins and arteries.
• Check if it is safe to do a procedure or surgery that might cause bleeding.
• Check how well the liver is working.

The activated partial thromboplastin time (APTT) test is used after you take blood-thinners to see if the right dose of medicine is being used. If the test is done for this purpose, an APTT may be done every few hours. When the correct dose of medicine is found, you will not need so many tests.

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