What are the effects of Vitamin K excess on hypercoagulability (increased tendency to form blood clots)?

From the Guidelines

Vitamin K excess can lead to a hypercoagulable state, particularly in patients with pre-existing risk factors such as atrial fibrillation, previous thromboembolism, or mechanical heart valves, and therefore, its use should be carefully managed to avoid overcorrection, as noted in the 2008 ACC/AHA guidelines 1. When considering the risks of vitamin K excess, it is essential to weigh the potential for hypercoagulability against the need for anticoagulation therapy.

• Patients on warfarin should maintain consistent vitamin K intake to avoid fluctuations in anticoagulation control, as excessive anticoagulation can be managed by withholding warfarin and monitoring INR levels 1.
• The use of low-dose intravenous vitamin K (1 mg) appears safe in situations where anticoagulation needs to be reversed, but high-dose vitamin K, especially parenteral vitamin K1, can increase the risk of overcorrection to a hypercoagulable state 1.
• Risk factors for hypercoagulability include atrial fibrillation, previous thromboembolism, LV dysfunction, hypercoagulable conditions, older-generation thrombogenic valves, mechanical tricuspid valves, or more than 1 mechanical valve, and these patients should be closely monitored when vitamin K is administered 1.
• To minimize the risk of hypercoagulability, patients should limit vitamin K supplementation to recommended daily allowances (90 mcg/day for women, 120 mcg/day for men) and avoid high-dose supplements unless medically prescribed, and maintain consistent consumption of vitamin K-rich foods like leafy greens if they are on warfarin therapy.
• Blood tests measuring clotting factors or INR can help monitor coagulation status in at-risk individuals, and healthcare providers should discuss vitamin K intake with patients who have known hypercoagulable conditions.

From the FDA Drug Label

When vitamin K1 is used to correct excessive anticoagulant-induced hypoprothrombinemia, anticoagulant therapy still being indicated, the patient is again faced with the clotting hazards existing prior to starting the anticoagulant therapy Phytonadione is not a clotting agent, but overzealous therapy with vitamin K1 may restore conditions which originally permitted thromboembolic phenomena.

Vitamin K excess can lead to a hypercoagulable state, as it may restore the conditions that originally permitted thromboembolic phenomena.

• Key point: Overzealous therapy with vitamin K1 should be avoided, as it may increase the risk of thromboembolic events.
• Clinical decision: Dosage should be kept as low as possible, and prothrombin time should be checked regularly as clinical conditions indicate 2.

From the Research

Vitamin K Excess and Hypercoagulable State

• Vitamin K plays a crucial role in blood coagulation, and its excess or deficiency can lead to various complications 3, 4.
• The risk of bleeding increases dramatically when the international normalized ratio (INR) exceeds 4.0-6.0, although the absolute risk of bleeding remains fairly low, <5.5 per 1000 per day 3.
• Vitamin K administration can help lower excessively elevated INR faster than withholding warfarin alone, but it has not been clearly demonstrated that vitamin K treatment lowers the risk of major hemorrhage 3, 5.

Treatment of Excessive Anticoagulation

• Oral vitamin K treatment is preferred over intravenous or subcutaneous routes due to the risk of anaphylactoid reactions or cutaneous reactions 3, 5.
• A dose of 1-2.5mg of oral phytomenadione (vitamin K(1)) can reduce the range of INR from 5.0-9.0 to 2.0-5.0 within 24-48 hours 3.
• The effectiveness of phytonadione (vitamin K) in treating excessive anticoagulation has been demonstrated in several studies, with oral and intravenous vitamin K being equivalent and more effective than subcutaneous vitamin K or placebo 5.

Monitoring Anticoagulant Therapy

• Established monitoring methods for heparin and warfarin include activated partial thromboplastin time (APTT)/anti-Xa assay and prothrombin time - international normalized ratio (PT-INR), respectively 6, 7.
• New generation anticoagulant drugs, called direct oral anticoagulants (DOACs), have been widely prescribed to prevent and treat several thromboembolic diseases, and their anticoagulant effects can be measured in specific clinical circumstances 6, 7.
• Laboratory guidance on the choice of the appropriate test to be ordered according to the drug being administered, as well as on appropriate interpretation of test results, is necessary for effective monitoring of anticoagulant therapy 7.