Subclinical hyperthyroidism seems not to have a significant impact on systemic anticoagulation in patients with coumarin therapy

SummaryThere is little data regarding the impact of subclinical hyperthyroidism on coagulation metabolism in patients undergoing systemic anticoagulation therapy with coumarin derivates. In this retrospective analysis we studied 233 patients with benign thyroid disorders receiving therapeutic iodine-131, as well as concomitant systemic anticoagulation therapy (subclinical hyperthyroidism: n=178; overt hyperthyroidism: n=15; euthyroidism: n=40). Multivariate regression analyses were performed in the total study population as well as in the subgroup of patients with subclinical hyperthyroidism to identify the possible impact of several variables on anticoagulation therapy, large enough to push the International Normalized Ratio (INR) level out of the therapeutic range (INR 3.0).Therapy with antibiotics or nitrates was significantly associated with INR-values >3.0 in the total population, while ACE inhibitors were associated with lower incidence of INR-values 3.0, whereas therapy with thyroid suppressive drugs or TSH-values