Anticoagulation Clinic

Safely manage warfarin treatment

When patients are diagnosed with a condition that requires them to take warfarin (known by the brand name Coumadin® or Jantoven®), their provider may refer them to the Anticoagulation Clinic for monitoring and dosing. Warfarin is a blood thinner that can help prevent and treat blood clots. It’s commonly used to manage the heart condition atrial fibrillation, among other diseases.

Warfarin requires ongoing monitoring with INR (international normalized ratio) testing, which measures how long it takes blood to clot. Patients can receive this test at any Vancouver Clinic laboratory—no appointment necessary. After each test, a nurse reaches out with results, dosing adjustments, future test dates, and warfarin prescription refills (as required). Nurses are available to discuss questions and concerns by phone and MyChart.

This consistent, expert monitoring helps keep patients healthy and safe. Registered nurses lead the Anticoagulation Clinic. They use evidence-based practices to determine dosing and test frequency and consult with referring providers as necessary.

My provider told me I need to start taking warfarin. What do I do now?
Your provider will submit a referral to the Anticoagulation Clinic. Once we receive the referral we will contact you. During that call, we will:

• Talk about your starting dose
• Schedule your next INR test
• Setup a one-on-one education session for a time that is convenient for you.

How long do I need to take warfarin?
Your provider will determine if you should take warfarin for a short-term or long-term period. Warfarin may be used for a short-term period to prevent blood clots after a knee or hip surgery. Patients with atrial fibrillation or a heart-valve replacement are likely to be on it longer.

How often will I need to test my INR?
Your blood will be tested more frequently when you are first starting, normally twice in the first week. Once you have reached the level determined by your provider, the time between tests will increase, provided you stay within your therapeutic range. The maximum time between tests is six weeks. If you test out of your therapeutic range, you will be asked to test again in four to 10 days. If you start a new medication, such as certain antibiotics, you may be asked to test in two to three days. We will do our best to determine return dates that are convenient, so let us know if there are days of the week that work better for your schedule.

Do I need to make an appointment to test my INR?
Anticoagulation Clinic nurses will put in a “standing order” so that you can go to any Vancouver Clinic location lab during their business hours and walk in at the time of day that works well for you.

About blood clots
About warfarin
About vitamin K

Warfarin works by blocking some of the body’s ability to use vitamin K, which is needed to make clotting factors. Bacteria in the intestinal tract naturally make vitamin K, and the body also receives it through food. Stress, over-the-counter and prescription medications, herbs, illness, and activity levels all influence the body’s metabolism and its ability to make vitamin K. How much vitamin K-rich food patients consume also has a big impact.

Vitamin K occurs in many healthy foods and is particularly high in green leafy vegetables (spinach, chard, and kale), Brussels sprouts, and broccoli. A cup of olive or soybean oil is also high in vitamin K.

When taking warfarin, meal consistency is key. Keeping servings of vitamin K-filled foods similar from week to week helps keep warfarin in a therapeutic range. Anticoagulation Clinic nurses work with patients to determine the level of warfarin that fits their eating habits. Alcohol can increase the INR, so patients may want to consider avoiding it or limiting their intake to one drink per day.

Here are some foods higher in vitamin K:

• Kale
• Swiss chard
• Broccoli
• Spinach
• Green and red leaf lettuce
• Escarole
• Endive
• Cabbage
• Liver
• Green peas

These foods have a moderate amount of vitamin K:

• Mustard greens
• Brussels sprouts
• Butter lettuce
• Watercress
• Yellow snap beans
• Kiwi fruit
• Asparagus
• Soybeans
• Split peas