We aimed to assess the ankle-brachial index (ABI) in patients with Graves' disease. In the cross-sectional assessments, 81 patients with drug-naive Graves' disease and 235 with euthyroidism were enrolled. ABI and vascular cell adhesion molecule-1 (VCAM-1) levels were assessed. In the prospective follow-up, 32 patients with Graves' disease were assessed again after antithyroid drugs for at least 4 weeks, and 32 age- and sex-matched controls with euthyroidism were also followed up. Patients with Graves' disease had a higher VCAM-1 level (1309 +/- 292 vs. 1009 +/- 168 ng/mL, P<0.001) and a lower ABI (0.98<plus/minus>0.11 vs. 1.06 +/- 0.10, P<0.001) than those with euthyroidism. ABI was significantly lower in patients with hyperthyroidism and a high VCAM-1 level than in those with euthyroidism and a low VCAM-1 level (regression coefficient: -0.050, 95% confidence interval [CI] between -0.080 and -0.019; P=0.001). After treatment with antithyroid drugs, the change in free thyroxine (T4) level was inversely associated with the percentage change in ABI (regression coefficient: -0.003, 95% CI between -0.005 and -0.001, P=0.001). A synergistic effect of VCAM-1 and free T4 on ABI reduction was observed. After a longitudinal follow-up, an increase in ABI was significantly correlated with a decrease in the free T4 level.
