Blood tests are done to check the prothrombin time. The prothrombin time is reported in a standardized form called the international normalized ratio (INR). The goal is to keep the INR within a certain range, usually between 2-3 by adjusting your dose of Coumadin. My test results came back 1.5. The doctor has increased my dosage to 7.5mg three days a week, 5mg the rest. I don't have to go have my blood drawn until the 19th. That makes it the first time since July I have gone over one week between blood tests. To me that is a big deal.