What does an elevated Prothrombin Time-International Normalized Ratio (PT-INR) indicate?

From the Guidelines

A high PT-INR indicates that your blood is taking longer than normal to clot, meaning you have an increased risk of bleeding, and according to the most recent guidelines 1, it is generally recommended to reduce the INR as soon as possible through the use of clotting factors, vitamin K, and/or fresh frozen plasma in the acute setting of a patient with an ICH or SDH.

Key Points to Consider

• Normal INR values for most people range from 0.8-1.2, while patients on blood thinners like warfarin typically have target ranges of 2.0-3.0 or 2.5-3.5, depending on their condition.
• A high PT-INR can result from anticoagulant medications (especially warfarin), liver disease, vitamin K deficiency, or certain genetic disorders.
• If you have an unexpectedly high INR, you may need dose adjustments of your anticoagulant medication or treatment for the underlying cause.
• Symptoms of concern include unusual bruising, nosebleeds, bleeding gums, blood in urine or stool, or severe headaches.

Management of High PT-INR

• The decision to restart antithrombotic therapy after ICH related to antithrombotic therapy depends on the risk of subsequent arterial or venous thromboembolism, the risk of recurrent ICH, and the overall state of the patient, as stated in the guidelines 1.
• Prothrombin complex concentrate, factor IX complex concentrate, and rFVIIa can normalize the laboratory elevation of the INR very rapidly, but with greater potential of thromboembolism 1.
• Regular monitoring is essential for patients on anticoagulant therapy to maintain the proper balance between preventing harmful clots and avoiding dangerous bleeding.

Important Considerations

• Elevated INRs have been shown to be associated with larger hematoma volumes when corrected for age, sex, race, antiplatelet use, hemorrhage location, and time from onset to scan 1.
• The presence of microbleeds on MRI may signify an underlying microangiopathy or the presence of cerebral amyloid angiopathy, and the risk of ICH in patients receiving anticoagulation is higher in patients with microbleeds 1.

From the FDA Drug Label

The following factors, alone or in combination, may be responsible for INCREASED PT/INR response:

• ENDOGENOUS FACTORS: blood dyscrasias — diarrhea hyperthyroidism see CONTRAINDICATIONS elevated temperature poor nutritional state cancer hepatic disorders steatorrhea collagen vascular disease infectious hepatitis vitamin K deficiency congestive heart failure jaundice
• EXOGENOUS FACTORS: Potential drug interactions with warfarin sodium tablets are listed below by drug class and by specific drugs.

A high PT-INR indicates that the blood is too thin and the patient is at a higher risk of bleeding. This can be caused by various factors, including certain medications, dietary changes, or underlying medical conditions. Key points to consider:

• Monitoring: Regular PT/INR monitoring is essential to ensure the patient's blood is within the therapeutic range.
• Dose adjustment: The dose of warfarin may need to be adjusted to achieve the desired PT/INR range.
• Bleeding risk: A high PT/INR increases the risk of bleeding, and patients should be closely monitored for signs of bleeding. 2

From the Research

Definition of PT-INR

• PT-INR (Prothrombin Time-International Normalized Ratio) is a test used to measure the time it takes for blood to clot and compare it to a standard sample 3.
• A high PT-INR indicates that the blood is taking longer than normal to clot, which can increase the risk of bleeding 4.

Causes of High PT-INR

• Warfarin therapy is a common cause of high PT-INR, as it works by inhibiting the production of vitamin K-dependent clotting factors 5.
• Other causes of high PT-INR include liver disease, vitamin K deficiency, and certain medications 6.

Reversing High PT-INR

• Prothrombin complex concentrates (PCCs) are effective in rapidly reversing warfarin anticoagulation and correcting high PT-INR [(3,4,5)].
• Fresh frozen plasma (FFP) is also used to reverse warfarin anticoagulation, but it may be less effective than PCCs in correcting high PT-INR [(3,5)].
• Vitamin K is also used to reverse warfarin anticoagulation, but it may take longer to take effect than PCCs or FFP 7.

Risks Associated with High PT-INR

• High PT-INR can increase the risk of bleeding, particularly in patients with traumatic intracranial hemorrhage [(4,7)].
• Reversing warfarin anticoagulation with PCCs or FFP can also increase the risk of thrombotic events, although this risk is generally considered to be low [(3,4)].