Understanding Your Labwork
Understanding Your Labwork
Getting started with monitoring
If you are taking warfarin, your doctor will ask that you regularly monitor the blood-clotting level to be sure your medication is working and the dose of warfarin is correct. Your result is written as a value called the INR (international normalized ratio) tests how quickly your blood clots. Another test sometimes used is called the prothrombin time or PT. The INR is the most commonly done to test how warfarin is working.
How does it work?
These tests are usually fairly easy to perform and the results are available right away. It requires a finger prick using a lancet which helps you gather a very small of your own blood. Within a few seconds of pricking your finger, a drop of blood should be placed into the tester. Your blood sample is then mixed with a laboratory chemical and timed to see how long it takes before a clot is formed.
What is the desired result?
People with AFib who are taking anticoagulant medications should generally have an INR between 2.0 and 3.0. In some cases, such as those with mechanical heart valves, the desired INR may be higher - about 2.5 to 3.5. The doctor will use the INR to adjust a person's drug dosage to get the clotting time or prothrombin time into the desired range that is right for the person and their condition.
Your warfarin dosage will be carefully adjusted to maintain an INR level appropriate for your individual needs and risks. For this reason, you will have the best results if you take your medicine exactly as prescribed. Have your blood tested regularly according to your doctor's orders. If you need heparin or low-molecular-weight heparin, blood tests are also required to check that the dose is correct.
What does my lab report tell me?
Your goal: the right clotting time
The goal of anticoagulation therapy is to lower the clotting tendency of your blood, not to prevent clotting completely. Your body will still need to be able to form clots in response to injury or situations like nose bleed.
Dosage may need adjustments
The effects of warfarin must be monitored carefully through regular blood testing. Unlike most medications that are administered as a fixed dose, warfarin dosing is adjusted according to the INR blood test results; therefore, the dose usually changes over time. Coumadin/warfarin pills come in different colors, and each color corresponds to a different dose.
How often should I test?
It is important to monitor the INR (at least once a month and sometimes as often as twice weekly) to make sure that the level of warfarin remains in the effective range. If the INR is too low, blood clots will not be prevented and you will be at risk of a stroke, but if the INR is too high, there is an increased risk of bleeding. This is why those who take warfarin must have their blood tested frequently, especially since the food you eat can impact your INR. It is a fine and important balance!
Coumadin/Warfarin is a medication that will require regular monitoring for as long you are taking it. It is important for reducing your risks, so you may want to adapt your routine to make monitoring and medication management a part of your life. There are many people who take this medication and learn to manage the related tasks and integrate it into their routine fairly smoothly.
If the impact of managing warfarin is too great, you may wish to discuss the newer anticoagulants referred to as "NOACs" (novel oral anticoagulants) with your doctor because they generally do not have food and drug interactions and do not require regular testing. In addition, the NOACs were either as good as, or better than, warfarin at stroke prevention, and caused fewer bleeding incidents.