What Is Warfarin (Coumadin)?

Warfarin is a prescription medication that is used to prevent harmful blood clots from forming or growing larger. Not all blood clots are harmful, some are even beneficial. However, certain medical conditions may cause harmful blood clots to form in areas of the body that they should not, such as the heart, brain and lungs.

How Does Warfarin Work?

Clot formation in the body is a very complex process that involves many substances called clotting factors. Warfarin blocks the type of clotting factor that requires Vitamin K to work properly. Although Warfarin is often called a “blood thinner”, it doesn’t actually thin the blood. It prevents the Vitamin K dependent clotting factors from working properly. As a result, the blood does not clot as rapidly, and this in turn prevents harmful blood clots from forming.

How Does My Diet Affect my Coumadin Level In My Body?

Warfarin blocks the Vitamin K dependent clotting factor, and much of the Vitamin K in our body comes from the food that we eat. Therefore it is important to eat a consistent amount of foods that contain Vitamin K.  The highest amount of Vitamin K is found in green and leafy vegetables. It is for this reason that patients who take Warfarin should be aware of the Vitamin K level in the foods that they eat, and to avoid sudden changes in diet. You do not need to avoid foods that contain Vitamin K, you just need to make sure that your daily level of Vitamin K is consistent. If your diet changes suddenly for any reason, such as illness or to lose weight, this may affect the level of vitamin K in your blood.  A sudden increase or decrease of Vitamin K in your diet can decrease or increase the effect of Warfarin.

What Else Can Affect the Coumadin level in My Body?

Besides green, leafy vegetables, some other foods may interfere with the effectiveness of Warfarin, such as:

 The most important thing to remember is to eat what you normally eat and do not make any sudden changes in your diet without notifying out Coumadin department.

Why Does My Blood Have to Be Monitored?

The purpose of Warfarin therapy is to decrease the clotting tendency of the blood, but not to prevent it from clotting completely. As we have established, many factors can increase or decrease the effectiveness of Warfarin. It is for these reasons that it is important to monitor the effect of Warfarin closely with blood testing.

The blood test used to measure the time it takes for blood to clot is referred to as a prothrombin time test, or protime (PT). The PT is reported as the International Normalized ratio (INR), which is a more standard way to express the PT value among different labs. The target range for your INR depends on your medical condition, or the reason for taking the Warfarin. It is important for you to know your target range and to also know your most recent INR result.

Where Can I Go To Get My INR Checked?

At Hamilton Cardiology Associates, we have a dedicated staff in our Coumadin Department who follow a specific dosing and monitoring protocol. Our staff is available to answer your questions and concerns and can be reached at 609-581-5704.  We offer many convenient options for INR monitoring.

We offer a daily clinic for Coumadin testing.  During this 15 minute appointment, our staff will

If these hours do not fit into your schedule, or if you have non-Medicare primary insurance and prefer to avoid a co-pay, we also have other options available. We can give you a prescription to go to your local lab (Labcorp, Quest, or a hospital lab). We will receive the result and discuss recommendations with you over the phone.  For patients who are receiving long term warfarin therapy, we may be able to request a home machine for you to test the INR yourself, if so desired.  With all of these options, the staff at Hamilton Cardiology is available to monitor your INR and manage your warfarin dosing.

How Often Do I Need to Check My INR?

Once the INR is consistently maintained in the target range, INR testing should be performed at least once a month.  However, if the INR is out of range, it should be performed more frequently. At Hamilton Cardiology Associates, we have dedicated staff in our Coumadin Department who follow a specific dosing and monitoring protocol. New changes in diet, new medication changes, stress and illness may all affect the INR level, and may require changes in your Warfarin dosing, even if your INR level was in the target range when last checked. If you experience any of these changes, it is important to notify the Coumadin Department.  They will check your INR more frequently and may possibly adjust the Warfarin dose, to ensure that your INR remains in the target range

When should I take my Warfarin?

Warfarin should be taken as prescribed in the evening. The dose of warfarin may vary from day to day, or may be changed, based on the INR level. It is very important that you take the medication as prescribed, in the evening.  If you miss a dose, do not try to “catch up”. Instead, call the coumadin department and they will provide you with dosing instructions.

What Are The Complications of Warfarin?

Frequent INR monitoring is often required to ensure that the INR level remains in the target range. This is the best way to minimize the chance of complications from having an INR level too high (chance of bleeding increased) or too low (chance of clotting increased). These are the two most serious complications of Warfarin therapy. Signs of unusual bleeding include:

In addition to these signs, additional symptoms that should be reported immediately to the Coumadin Department include:

How Can I Prevent Complications of Warfarin Therapy?

The most important thing you can do to prevent complications from Warfarin therapy is to be an active participant in your care or in the care of your loved one. Compliance with the recommended medication dosing and INR testing schedule is crucial for success, as well as an open communication with our Coumadin Department. It is very important to report new medication changes (including antibiotics, herbal medicines, and over the counter medications), changes in weight or diet, sudden illness, or and other changes in your lifestyle. If you accidently miss a dose, do not double the dose to “catch up”. Instead, call our Coumadin Department.

Other simple changes to decrease the risk of bleeding while taking Warfarin include the following: 

What Other Resources Are Available for Me?

There are a number of resources available on the internet, but it can be difficult to know which ones are reputable. Some recommended sites include:

The National Institutes of Health: www.cc.nih.gov/ccc/patient_education/drug_nutrient/coumadin1.pdf

Dr Gourmet: www.drgourmet.com/warfarin

The North American Thrombosis Forum: www.natfonline.org/patients

American Heart Association: www.heart.org