Lack of significant association between intima-media thickness in the carotid artery and serum TSH level. The Tromsø Study.
BACKGROUND
Increased arterial wall intima-media thickness (IMT) is an early feature of atherosclerosis and has been reported to be altered in patients with thyroid dysfunction. The present study was performed to examine the relation between carotid artery intima-media thickness and possible variations in thyroid function in normal subjects using serum TSH as a surrogate index of thyroid function.


METHODS
A total of 2034 subjects (974 males) were studied, 1856 or whom were non-users of thyroxine. The subjects not taking thyroxine were classified into three groups, those with a low serum TSH (0.48 mIU/L (2.5 percentile, those with serum TSH from 0.48 to 4.16 mIU/L, and those with high serum TSH of >4.16 mIU/L (97.5 percentile). Carotid ultrasound was performed in each all 2034 subjects to determine IMT.


RESULTS
Among those not taking thyroxine, subjects in the low serum TSH group had a higher mean IMT as compared to those in the normal and high serum TSH groups but the differences were not significant when adjusted for gender, age, smoking status, body mass index, systolic blood pressure and serum cholesterol (0.88 +/- 0.15 mm, 0.84 +/- 0.16 mm, and 0.84 +/- 0.24 mm respectively). Subjects taking thyroxine had significantly higher IMT than those not taking thyroxine (0.89 + 0.20 mm versus 0.84 + 0.17 mm, p<0.01).


CONCLUSIONS
No significant relationship between carotid IMT and serum TSH levels was observed in normal, non thyroxine taking, subjects. Carotid IMT was increased in subjects taking thyroxine. Whether the increase in carotid IMT is due to thyroxine ingestion or underlying thyroid disease cannot be answered from the study.
Jorde
Rolf
R
Institute of Clinical Medicine, University of Tromsø, Tromsø, Norway. rolf.jorde@unn.no
Joakimsen
Oddmund
O
Stensland
Eva
E
Mathiesen
Ellisiv B
EB
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002318:Cardiovascular Diseases / Q000097:blood / Q000473:pathology; D002339:Carotid Arteries / Q000000981:diagnostic imaging / Q000473:pathology*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D009664:Norway; D013972:Thyrotropin / Q000097:blood*; D017539:Tunica Intima / Q000000981:diagnostic imaging / Q000473:pathology*; D017540:Tunica Media / Q000000981:diagnostic imaging / Q000473:pathology*; D018617:Ultrasonography, Doppler, Pulsed
D013972:Thyrotropin