Warfarin inhibits vitamin K dependent coagulation factors. It is used to thin the blood and is prescribed in the following conditions: heart arrhythmias (atrial fibrillation), stroke, heart stents, deep vein thrombosis (blood clot), pulmonary embolus (blood clot of the lung), mechanical heart valves, and hyper-coagulable disorders. The patient's blood is checked periodically to monitor the effectiveness of the medication. Dietary changes and new medications can alter the effects of the drug causing either too much or too little anti-coagulation.
Description
Warfarin inhibits vitamin K dependent coagulation factors. It is used to thin the blood and is prescribed in the following conditions: heart arrhythmias (atrial fibrillation), stroke, heart stents, deep vein thrombosis (blood clot), pulmonary embolus (blood clot of the lung), mechanical heart valves, and hyper-coagulable disorders. The patient's blood is checked periodically to monitor the effectiveness of the medication. Dietary changes and new medications can alter the effects of the drug causing either too much or too little anti-coagulation.
Symptoms
Too much medication can cause: nosebleeds, bleeding gums, vomiting blood, vomiting coffee grounds, bloody stools, black stools (melena), easy bruising, dizziness, fainting, confusion.
Tests
Common tests used for diagnosis and treatment
Workup:
Blood tests are performed periodically to measure the Prothrombin Time (PT), which is converted to a value called the INR (International Normalized Ratio). The target INR range is usually between 2 and 3, although people with a mechanical heart valve or a hyper-coagulable state may need to run a higher INR.
Other Specific Tests: PT (Protime)
Specialists:
Internal Medicine, Pediatrics, Family Practice, Blood and Cancer Care (hematology and oncology), Pediatric Hematology and Oncology
Workup:
Blood tests are performed periodically to measure the Prothrombin Time (PT), which is converted to a value called the INR (International Normalized Ratio). The target INR range is usually between 2 and 3, although people with a mechanical heart valve or a hyper-coagulable state may need to run a higher INR.
Other Specific Tests: PT (Protime)
Specialists:
Internal Medicine, Pediatrics, Family Practice, Blood and Cancer Care (hematology and oncology), Pediatric Hematology and Oncology
Treatment
The patient's blood is monitored to ensure the PT/INR is therapeutic. Patients with an INR above the target range are at increased risk of bleeding. Those with an INR below the target range are at risk of unwanted clotting. In both situations, more frequent monitoring is needed.