Impact of thyroid metabolism on the course of INR levels in a patient with systemic anticoagulation suffering from amiodarone-induced thyrotoxicosis.

We report the case of a 60 year old female patient on continuous systemic anticoagulation therapy with coumarin due to mechanical aortic valve replacement and a more than 3 years lasting amiodarone therapy due to severe ventricular extrasystoles suffering from amiodarone induced thyrotoxicosis (AIT). During the course of AIT, showing different thyroid metabolic conditions, INR levels revealed a course closely related to the thyroid conditions indicating a significant and clear-cut effect of both hyper- and hypothyroidism on systemic anticoagulation therapy with coumarin. This continuous interaction of different thyroid metabolic conditions and the anticoagulation state could be well documented in the presented case over a time period of approximately five months.