Many people need to take oral anticoagulant medications such as Coumadin. These drugs interfere with the action of Vitamin K that is necessary for the formation of factors that cause the blood to clot. Thus, Coumadin impairs blood clotting and is given to people who have conditions where unwanted clotting may occur.  Examples of such conditions are: thrombophlebitis, heart conditions, and pulmonary embolism.

To assess whether a patient’s anticoagulant drug dosage is appropriate, a blood test known as the INR (International Normalized Ratio) or Prothrombin Time can be performed.  This test measures the time that it takes for the patient’s blood to form a clot and compares this to normal, unmedicated persons. The goal is to maintain the patient’s INR elevated to a level that minimizes the risk of clotting.

A number of things will interfere with the action of the Coumadin and therefore will change the INR value. The INR may be increased by: underlying diseases that change Coumadin’s activity, numerous drugs, elevated temperature, alcohol, flu vaccine, dietary deficiency and change in diet.  The INR may be decreased by: underlying disease, a variety of drugs, and change in diet.  People taking Coumadin should not take any other drugs (or over-the-counter preparations) without consulting their physician.

Many patients monitor their own INR with their physician’s guidance. MDS Metro will provide patients with their own results by phone after permission to do this has been obtained from their doctor.