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-T4) replacement might affect serum markers of endothelium injury, including von Willebrand factor (vWF), factor VIII activity and thrombomodulin (TM), during normalization of increased intima-media thickness (IMT) in the common carotid artery (CCA) in hypothyroid patients after L-T4 replacement therapy.


METHODS
Thirty-three hypothyroid patients were examined for vWF, factor VIII, TM and CCA IMT before and after 1 year of normalization of thyroid function by L-T4 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 1 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-T4 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-T4 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-T4 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.
Nagasaki
Toshiki
T
Department of Metabolism, Endocrinology and Molecular Medicine, Osaka City University Graduate School of Medicine, 1-4-3, Asahi-machi, Abeno-ku, Osaka 545-8585, Japan.
Inaba
Masaaki
M
Henmi
Yasuko
Y
Kumeda
Yasuro
Y
Ueda
Misako
M
Tahara
Hideki
H
Ishimura
Eiji
E
Onoda
Naoyoshi
N
Ishikawa
Tetsuro
T
Nishizawa
Yoshiki
Y
D015415:Biomarkers / Q000097:blood; D002340:Carotid Artery Diseases / Q000097:blood / Q000000981:diagnostic imaging* / Q000209:etiology; D005169:Factor VIII / Q000032:analysis; D005260:Female; D020249:Hormone Replacement Therapy; D006801:Humans; D007037:Hypothyroidism / Q000150:complications / Q000000981:diagnostic imaging / Q000188:drug therapy*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012044:Regression Analysis; D044967:Serum / Q000737:chemistry; D018180:Thrombomodulin / Q000097:blood; D013974:Thyroxine / Q000627:therapeutic use*; D017539:Tunica Intima / Q000000981:diagnostic imaging*; D017540:Tunica Media / Q000000981:diagnostic imaging*; D014463:Ultrasonography; D014841:von Willebrand Factor / Q000032:analysis*
D015415:Biomarkers; D018180:Thrombomodulin; D014841:von Willebrand Factor; D005169:Factor VIII; D013974:Thyroxine