Why monitor warfarin use?

Staying on top of your PT/INR helps you stay healthy

If you are taking warfarin, then PT/INR, or INR, testing is a required part of your ongoing therapy. PT stands for “prothrombin time,” the time it takes for blood to clot. INR stands for “international normalized ratio,” a calculation for making results consistent no matter what type of test was used.

Your PT/INR results let your doctor know whether you’re taking the right amount of warfarin to keep you in range and on track. Testing is a continual commitment between you and your doctor. However, once you know your options, you’ll see how it can become a simple part of your routine.

 

 
what is warfarin

 

Learn how warfarin works

Often called blood thinners, anticoagulants like warfarin (also called Coumadin®) help increase the time it takes for your blood to clot.1 For instance, if you’re taking warfarin and you cut your finger, it may take longer for the bleeding to stop than for somebody who isn’t taking an anticoagulant. 

While several types of anticoagulants are available, warfarin is the most widely used blood thinner in the world.2

How warfarin works

Vitamin K plays a key role in forming clotting factors, which causes the blood to clot. Warfarin blocks the formation of vitamin K-dependent clotting factors, which helps prevent and slow the formation of harmful clots. 

Who takes anticoagulants?

If you just found out from your doctor that you need to start taking warfarin, you’re not alone. Every day, millions of people worldwide take anticoagulants.3 They are commonly prescribed for or as a result of:4

• Atrial fibrillation (irregular heartbeat)

• Mechanical heart valves

• Venous thromboembolism

• Thrombophilia (tendency to cause blood clots)

• Heart attack (causing damage to heart muscle)

• Stroke

 
warfarin at a glance, tablet, most widely used anticoagulant in the world, must be regularly monitored, may need to take a period of weeks, months, or years.

+References

1 http://www.stoptheclot.org/learn_more/blood_clot_treatment.htm (accessed January 2018).

2 Wardrop, D. et al. (2008). British Journal of Haematology 141:757-763.

3 http://www.ismaap.org/welcome-detail/management-of-longtime-anticoagulation/ (January 2018)

4 Ryan, J. et al. (2008). Journal of Clinical Pharmacy and Therapeutics 33:581-590

5 Fiumara, K. et al. (2009). Circulation 119:e220-e222.

heart-check

If you have any questions about PT/INR, talk to your doctor. 

 
know your number

 

Keeping your PT/INR in range is key

When you’re prescribed warfarin, regular blood tests are required to ensure your blood isclotting within a target range.1 This is called PT/INR, or INR, monitoring. 

An INR test shows how quickly your blood will clot while you’re on your current dose of warfarin, which helps determine whether your dose needs to be adjusted.

Your individual target range may vary based on disease state and advising doctor’s treatments.

For more information on your range, please contact your doctor. 

 
What does PT/INR mean? PT stands for prothrombin time, the time it takes for blood to clot. INR Stands for international normalized ratio, a calculation for standardizing results from different pt tests. Whats your target inr? Your clinician will provide you with a target INR range. For people taking warfarin, the targetINR typically ranges from 2 to 3, but may be different depending on the patient and his or her condition.2  Your individual target range may vary based on disease state and advising doctor’s treatments.For more information on your range, please contact your doctor. Risk of blood clots, venous thromboembolism, brain hemorrhage

+References

1 American Heart Association, “A patient’s guide to taking warfarin,” http://www.heart.org/HEARTORG/Conditions/Arrhythmia/PreventionTreatmentofArrhythmia/A-Patients-Guide-to-Taking-Warfarin_UCM_444996_Article.jsp (accessed January 2018).

2 Levi, M. et al. (2009). Seminars in Thrombosis Hemostasis 35:527-542.

 
ways to test

 

There are three ways to test your PT/INR

All three ways provide accurate results. However, many warfarin patients choose self-testing for the freedom and convenience it offers.

Wondering if self-testing is right for you? Take the assessment to find out. If you are ready for self-testing, download our Get Started Guide.

 
lab testing, in-office testing, self testing

 

Compare testing options

Think about which option works best for you and your lifestyle. All three options provide accurate PT/INR results. 

 
accurate and reliable test results, one drop of blood, small, portable meter, results in one minute, test anywhere, anytime, no trip to the doctor's office or lab, self-testing, office testing, lab testing.

+References

1 The CoaguChek XS system may be used up to a maximum altitude of 14,000 feet. Internet availability required for wireless reporting. 2net™ Hub transmitter works only in the United States and requires a reliable cellular connection.

 
your diet and warfarin

 

Learn how certain foods can impact your PT/INR

Like other medications, warfarin can be affected by what you eat and drink. While no foods are off limits, there are three important factors you need to consider.

 
1. Watch your vitamin K intake.  Produced by your body as part of the clotting process, vitamin K is alsofound in many green, leafy foods, such as kale, lettuce, spinach and broccoli. High amounts of vitamin K can reverse warfarin’s blood-thinning effect.1  Does this mean you should cut back on foods high in vitamin K?No, but a consistent diet is important, as your doctor will base yourrecommended warfarin dose on your regular diet. Consult your doctor with dietary concerns. 2. Avoid alcohol.  Because it immediately decreases your blood’s ability to clot, alcohol should be avoided when taking warfarin. Even if your PT/INR levels remain within the target range, the risk of major bleeding is increased.3 What’s more, after episodes of excessive drinking, clotting can increase, putting you at greater risk of heart attack or stroke.4 3. Tell your doctor about other medications and supplements.  Because warfarin can interact with many drugs and supplements,5, 6, 7  tell your healthcare provider about everything you take, including these  over-the-counter medications and supplements:  • Acetaminophen (e.g., Tylenol) • Aspirin, including ointments/creams • Ibuprofen (e.g., Advil) • Naproxen (e.g., Aleve) • Non-steroidal anti-inflammatory drugs (NSAIDs) • Heartburn or acid reflux medicines (e.g., Nexium, Zantac) • Cold/allergy medicines • Antibiotics • Herbal supplements (e.g., Ginkgo biloba, ginseng, St. John’s wort) • Birth control pills • Vitamin supplements with vitamin K
 

+References

1 Blood Thinner Pills: Your Guide to Using Them Safely. Agency for Healthcare Research and Quality, Rockville, MD. September 2015. Available at https://www.ahrq.gov/sites/default/files/wysiwyg/patients-consumers/diagnosis-treatment/treatments/btpills/btpills.pdf (Accessed January 2018.)

2 USDA. (Last modified May 2016). USDA National Nutrient Database for Standard Reference, Release 28, Vitamin K Content of Selected Foods (accessed January 2018).

3 American Heart Association. “A patient’s guide to taking warfarin.” http://www.heart.org/HEARTORG/Conditions/Arrhythmia/PreventionTreatmentofArrhythmia/A-Patients-Guide-to-Taking-Warfarin_UCM_444996_Article.jsp (accessed January 2018).

4 Renaud, S.C. and Ruf, J.C..(March 15, 1996). “Effects of alcohol on platelet functions.” Clinica Chimica Acta  246(1-2):77-89. http://www.ncbi.nlm.nih.gov/pubmed/8814972 (accessed January 2018).

5 Coumadin (warfarin sodium) [package insert 293US11PBS01503]. (2011). Princeton, NJ: Bristol-Myers Squibb.

6 Agency for Healthcare Research and Quality, Rockville, MD.  (August 2010). “Blood Thinner Pills: Your Guide to Using Them Safely.”, http://www.ahrq.gov/patients-consumers/diagnosis-treatments/btpills/btpills.html#using (accessed January 2018)

7 Mayo Clinic. “Warfarin side effects: Watch for interactions.” http://www.mayoclinic.org/diseases-conditions/deep-vein-thrombosis/in-depth/warfarin-side-effects/art-20047592?pg=2 (accessed January 2018).

 

 

 

frequently asked questions about pt/inr monitoring
CoaguChek Patient Why Test FAQ Icon

What is coagulation?

Coagulation is the formation of blood clots inside the body. Proteins in the blood, called fibrins, and small elements in the blood, called platelets, work together to form a clot, which helps stop bleeding when you have a cut or injury.

What are anticoagulants?

Oral anticoagulants (blood thinners) such as warfarin or Coumadin® are drugs that help thin the blood of patients with conditions such as atrial fibrillation, thrombophilia and other diseases that increase the risk of forming blood clots. Patients taking warfarin have to sometimes make a lifelong commitment to this medication to avoid complications such as stroke or pulmonary embolism (blockage in the main lung artery).

These drugs are called vitamin K antagonists, and each patient reacts to them differently. There are also external factors that could interfere with the medication, including certain foods, stress and alcohol. That is why it is so important for anticoagulation patients to test according to a prescribed testing frequency.1

Why do I need warfarin?

For some people, blood clots form too easily, or they don’t dissolve properly. These clots can impede blood flowing through the body, potentially leading to heart attack or stroke.2 Anticoagulation medication such as Coumadin® or another brand of warfarin slows down the clotting process to help keep you in a safe range.

What is PT/INR?

PT stands for “prothrombin time,” or the time it takes for blood to clot. INR is short for “international normalized ratio.” This is a calculation for standardizing results from PT tests. Essentially, PT/INR is a measure of whether your blood is clotting at a safe rate. You may see this referred to as PT monitoring, INR monitoring, or PT/INR.

What health conditions require PT/INR testing?

Any condition that results in an increased risk for blood clots and is treated with warfarin (sometimes known as Coumadin® or other brand names) will require regular testing. These include:3

  • Atrial fibrillation – The most common type of arrhythmia or irregular heartbeat.
  • Venous thromboembolism (VTE) – Involving blood clots in the veins of the legs or the lungs; includes deep vein thrombosis (DVT) and pulmonary embolism (PE).
  • Mechanical heart valves – Implantable devices, especially those with manmade surfaces, can cause blood clots to form.
  • Thrombophilia – An increased tendency to form abnormal blood clots.

What’s the target range of PT/INR?

The goal of monitoring your warfarin dose is to remain in the target range recommended by your doctor. For most people, a result of 2.0 to 3.0 is appropriate, although those at higher risk of clotting may have a target range of 2.5 to 3.5.4 Talk to your doctor about the appropriate range for you.

What if my results are out of range?

If your INR is higher than the target range, blood clots may not form quickly enough, and you may experience bruising or be at increased risk of bleeding. If your PT/INR is too low, you may still be at risk of excessive clotting.4

What can affect my PT/INR level?

Many things can alter your PT/INR, including stress, missing a warfarin dose, taking herbal supplements and other medications, and consuming certain foods and beverages, such as kale and cranberry juice. Talk to your doctor about what’s appropriate for you.

Can I drink alcohol while taking warfarin/Coumadin®?

Alcohol can increase the effect of warfarin and further slow your clotting rate, causing your INR to be too high. You may want to avoid it while on warfarin.5  Talk to your doctor about what’s appropriate for you. 

What’s the importance of vitamin K?

Warfarin works by blocking the body’s ability to use vitamin K, a necessary component in the formation of blood clots. When you’re taking warfarin, it’s important to keep the amount of vitamin K in your diet consistent, or it may impact the effectiveness of your warfarin doses.5

What foods are high in vitamin K?

Green vegetables such as spinach, kale and broccoli are high in vitamin K,6 as are the following foods:

  • Tuna
  • Prunes
  • Green tea
  • Beef and chicken liver
  • Liverwurst
  • Blueberries and blackberries 

How often should I test?

Test frequency should be determined by your doctor. 

 

+References

1 Coumadin® (warfarin sodium) package insert revised October 2011.

2 American Heart Association. “What is excessive blood clotting (hypercoagulation)?” http://www.heart.org/HEARTORG/Conditions/More/What-Is-Excessive-Blood-Clotting-Hypercoagulation_UCM_448768_Article.jsp (accessed January 2018).

3 Ryan, J. et al. (2008). Journal of Clinical Pharmacy and Therapeutics 33:581-590.

4 American Heart Association. “A patient’s guide to taking warfarin,” http://www.heart.org/HEARTORG/Conditions/Arrhythmia/PreventionTreatmentofArrhythmia/A-Patients-Guide-to-Taking-Warfarin_UCM_444996_Article.jsp (accessed January 2018).

5 Blood Thinner Pills: Your Guide to Using Them Safely. Agency for Healthcare Research and Quality, Rockville, MD. September 2015. Available at https://www.ahrq.gov/sites/default/files/wysiwyg/patients-consumers/diagnosis-treatment/treatments/btpills/btpills.pdf (Accessed January 2018.)

6 Mayo Clinic. “Warfarin diet: What foods should I avoid?” http://www.mayoclinic.com/health/warfarin/AN00455 (accessed January 2018).