Synonyms: Activated Partial Thromboplastin Time; aPTT; PTT

Why It Is Done

• Determine a possible cause for abnormal bleeding or bruising.
• Monitor the effects of the medication warfarin (Coumadin), which is used to prevent blood clots
• Screen for deficiencies of certain blood clotting factors.
• Screen for a vitamin K deficiency. Adequate
• Monitor liver function.

Test Overview

Partial thromboplastin time (PTT), measures the function of several other clotting factors. Partial thromboplastin time is often measured along with prothrombin time to evaluate bleeding abnormalities. These two tests together screen for problems with the normal blood clotting process and can detect most blood clotting problems caused by abnormal amounts of coagulation factors.

How To Prepare

No special preparation is necessary.