WHAT IS A PT/INR LAB TEST?
The Prothrombin Time (PT) Test is a blood test used to measure the body’s ability to form blood clots and the time is measured against the International Normalized Ratio (INR).
AM I REQUIRED TO FAST FOR THIS LAB TEST?
WHAT IS THE PRICE OF A PT/INR LAB TEST?
*Price may vary by location – contact your local ANY LAB TEST NOW®
In most people when an injury occurs, blood clotting is initiated to stop bleeding and to begin the healing process. Platelets (small, sticky cell pieces) adhere to the clot and a fibrous net begins to form to cover the injury site. This is called the “coagulation cascade” as many different clotting factors are involved and each must occur properly and in the right order for clotting to occur. If any of these factors are not functioning properly, improper healing and excessive bleeding can occur.
Patients at risk for blood clots that can lead to stroke and heart attack may be prescribed an anti-coagulant (blood-thinning) medication to help prevent stroke, embolism (free floating blood clots) and heart attack. Other uses for warfarin are atrial fibrillation (irregular heart beat), artificial heart valves, deep venous thrombosis (blood clots in the veins) and pulmonary embolism in which clots form in the veins and travel throughout the body. The PT test measures the speed of blood clot formation in seconds and is compared to the normal range for healthy individuals. The World Health Organization (WHO) has developed and recommends the use of the International Normalized Ratio (INR) for standardized testing for individuals receiving the anti-coagulant, warfarin.
WHY DO I NEED A PT/INR?
Are you taking the blood-thinning medication warfarin? Do you suspect you may have a bleeding disorder?
People susceptible to blood clots that can cause strokes and heart attacks may be taking anti-coagulant medications, such as warfarin, to reduce the formation of clots in the blood. While on warfarin it is important to monitor the effectiveness of the medication: Is it working to prevent blood clots? This allows your physician to adjust the dosage to achieve the best possible results and prevent devastating strokes due to embolisms, to ensure smooth operation of artificial heart valves and to treat deep venous thrombosis.
If you have experienced unexplained bruising or excessive bleeding your physician may recommend the PT and INR in conjunction with other blood clotting tests, such as the Activated Partial Thromboplastin Time Test (aPTT) to determine whether you have a bleeding disorder such as von Willebrand disease or hemophilia, or have a vitamin K deficiency or liver damage which is preventing the blood from clotting properly.
The range for healthy individuals who are not on anti-coagulant medication is 1.0-1.5 seconds.
For patients on warfarin the normal range is 2.0-3.0 seconds.
High, or prolonged, results may indicate liver disease, vitamin K deficiency, von Willebrand disease or hemophilia.
Shortened time periods for blood clotting may indicate a need to increase the dosage of warfarin to prevent stroke or heart attack from excessive formation of blood clots.
WHAT TYPE OF PHYSICIAN SHOULD I SEE?
You should see your primary care physician, cardiologist or a hematologist.