Why is it necessary to monitor patients on Vitamin K antagonists closely?

Monitoring patients on Vitamin K antagonists closely is crucial because these medications require lifelong management of blood levels to ensure the appropriate therapeutic range is maintained. Vitamin K antagonists, such as warfarin, work by inhibiting the action of vitamin K, which is necessary for the synthesis of several clotting factors. This mechanism helps prevent thromboembolic events, especially in patients with conditions like atrial fibrillation or those with a history of venous thrombosis.

When patients are on these anticoagulants, their INR (International Normalized Ratio) must be routinely monitored to ensure that it stays within a target range. If the levels are too low, there is a risk of clot formation, while levels that are too high can lead to bleeding complications. Thus, regular monitoring is integral to balancing the effectiveness of the treatment while minimizing risks associated with under- or over-anticoagulation.