How do blood thinners work?
Blood thinners work by blocking substances (clotting factors or thrombin) in the blood that are needed to form a clot. This keeps new clots from forming and existing clots from getting bigger. Even though they are sometimes called blood thinners, they do not thin the blood. Warfarin and heparin are the two main anticoagulant medicines. You take warfarin (Coumadin) as a pill. Heparin is given intravenously (through the vein) or as a shot. Both require close monitoring with blood tests. What kind of monitoring do I need? If you take warfarin (Coumadin), you need to a have test called prothrombin (pro-time or PT). The results of the test are usually reported as an “INR” (international normalized ratio). This is a method to make results standard among labs using different methods. For this test, a small sample of blood is taken and tested to see how long it takes your blood to clot. Your doctor may adjust your dose of blood thinners based on these results. When you first start taking warfa
