Decrease in carotid intima-media thickness in hypothyroid patients after normalization of thyroid function.
OBJECTIVE
This case-control study was carried out to assess whether levothyroxine (L-T4) replacement might cause regression of the enhanced atherosclerosis seen in hypothyroid patients.


METHODS
Intima-media thickness (IMT) in the common carotid artery (CCA) was measured from digitalized still images taken during scanning by high-resolution ultrasonography as an indicator of early atherosclerosis. Thirty-five hypothyroid patients were examined for their CCA IMT before and 1 year after normalization of thyroid function by L-T4 replacement. As control, 35 healthy subjects were enrolled from among the participants in a local health-check programme conducted at the Osaka City University Hospital.


RESULTS
Basal CCA IMT was significantly higher in hypothyroid patients [0.635 +/- 0.018 (mean +/- SE) mm] than in control subjects (0.559 +/- 0.021 mm, P < 0.005). After 1 year of euthyroidism, 34 out of 35 patients showed a significant decrease of CCA IMT, to 0.552 +/- 0.015 mm (P < 0.0001), a level comparable to normal controls. CCA IMT change was closely associated with basal levels of total cholesterol (r = -0.472, P= 0.0031), low-density lipoprotein (LDL) cholesterol (r = -0.441, P= 0.0076) and the total/HDL cholesterol ratio (r =-0.435, P= 0.0057), but not with any of the other variables measured except for age (r = -0.353, P= 0.0296).


CONCLUSIONS
This study demonstrated that L-T4 treatment might have the potential to reverse the progression of atherosclerosis in hypothyroid patients. Furthermore, it suggests that increased levels of LDL cholesterol and the total/HDL cholesterol ratio have an important role in the increased common carotid intima-media thickness 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
Sugiguchi
Shigeru
S
Fujiwara
Shigehiko
S
Emoto
Masanori
M
Ishimura
Eiji
E
Onoda
Naoyoshi
N
Ishikawa
Tetsuro
T
Nishizawa
Yoshiki
Y
D002340:Carotid Artery Diseases / Q000097:blood / Q000000981:diagnostic imaging / Q000209:etiology; D017536:Carotid Artery, Common / Q000000981:diagnostic imaging*; D016022:Case-Control Studies; D002784:Cholesterol / Q000097:blood; D008076:Cholesterol, HDL / Q000097:blood; D008078:Cholesterol, LDL / Q000097:blood; D005260:Female; D006801:Humans; D007037:Hypothyroidism / Q000097:blood / Q000000981:diagnostic imaging* / Q000188:drug therapy*; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012307:Risk Factors; D013974:Thyroxine / Q000627:therapeutic use*; D017539:Tunica Intima / Q000000981:diagnostic imaging*; D014463:Ultrasonography
D008076:Cholesterol, HDL; D008078:Cholesterol, LDL; D002784:Cholesterol; D013974:Thyroxine