Will I need frequent blood tests if I take a novel anticoagulant?

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Douglas E. Severance, MD
Family Medicine
If you take warfarin for atrial fibrillation, a common heart rhythm problem, you may be used to weekly or monthly lab work to make sure the warfarin is working effectively. Studies show that unlike warfarin, frequent blood tests are not needed with a novel anticoagulant. With warfarin, regular blood tests are done to check prothrombin time (also called PT or INR). This reading gives an indication of how the warfarin is working to prevent blood-clots. If your PT/INR time is too high, you have an increased risk of bleeding. If your PT/INR is too low, the warfarin is not working well enough, and you could form dangerous blood clots. If the PT/INR is in the correct range, it means that the warfarin is working the way it should. This correct range or “therapeutic window” is a very small one. Because it is so easy for warfarin levels be too high or too low, your doctor must check frequently to make sure you are in the safe range. With a novel anticoagulant, blood tests such as PT/INR are no longer used. You can start the medicine when your doctor prescribes it and not need monitoring of your PT/INR after that time.