Abstract
A 72-year-old man receiving warfarin to prevent throm-boembolism related to atrial fibrillation/flutter experienced a significant increase in the international normalized ratio (INR) after discontinuing an over the counter nutritional supplement containing vitamin K. Laboratory testing revealed critical elevations of INR and prothrombin time. After resumption of the nutritional supplement, the patient's laboratory values returned to within the desired range. With the explosion in popularity of herbal products, practitioners need to be aware of all nutritional supplements being consumed by patients as well as over the counter drugs.
Key Words: