Change in von Willebrand factor and carotid intima-media thickness in hypothyroid patients with normal thyroid function after levothyroxine replacement therapy

Objective: This study examined whether levothyroxine (L-T-4) replacement might affect serum markers of endothelium injury, including von Willebrand factor (vWF), factor WIT activity and thrombomodulin (TM), during normalization of increased intima-media thickness (IMT) in the common carotid artery (CCA) in hypothyroid patients after L-T-4 replacement therapy. Patients and methods: Thirty-three hypothyroid patients were examined for vWF, factor VIII, TM and CCA IMT before and after I year of normalization of thyroid function by L-T-4 replacement. CCA IMT was measured from digitized still images taken during scanning by high-resolution ultrasonography as an indicator of early atherosclerosis. Results: Serum factor VIII and vWF increased significantly during I year of normalization of thyroid function (from 122.7 +/- 9.4 to 151.3 +/- 18.8% (P < 0.05) and from 109.9 +/- 9.6 to 135.2 +/- 12.4% (P < 0.005) respectively), although these values all fell within the respective normal range. Serum TM, in contrast, did not change appreciably in response to L-T-4 treatment, moving from 2.57 +/- 0.15 to 2.74 +/- 0.18 ng/ml (P = 0.086). During 1 year of a euthyroid state, all patients showed a significant decrease in CCA IMT (P < 0.0001). Change in serum vWF, but not in factor VIII or TM, showed a positive correlation with that of CCA IMT during L-T-4 replacement therapy. Furthermore, the change in serum vWF was significantly and independently associated with change in CCA IMT (r = 0.490, P = 0.0038). Conclusions: The present study demonstrated that the improvement of CCA IMT during L-T-4 treatment might have the potential to attenuate an elevation of vWF and to attenuate vascular injury by the cardiovascular effects of thyroid hormone in hypothyroid patients.