The association of thyroid function with carotid artery plaque burden and strokes in a population-based sample from a previously iodine-deficient area.

BACKGROUND: Thyroid dysfunction is associated with detrimental cardiovascular effects. We analyzed whether thyroid status is related to carotid artery plaques and prevalent strokes. DESIGN, PATIENTS AND MEASUREMENTS: Data from 2128 subjects (1157 men and 971 women) aged > or =45 years without thyroid diseases participating in the Study of Health in Pomerania were analyzed. The presence of carotid plaques was assessed by B-mode ultrasound and prevalent stroke was assessed by interview. The sample was divided according to the reference range of serum TSH levels into decreased (<0.25 mIU/l), normal (0.25-2.12 mIU/l), and elevated (>2.12 mIU/l). Logistic regression models were adjusted for common confounders including age, sex, BMI, hypertension, diabetes mellitus, smoking, school education, plasma fibrinogen and serum cholesterol levels, and statins.
RESULTS: The prevalence of carotid plaques at any site was higher in subjects with decreased serum TSH levels (81.7%) compared with normal serum TSH levels (70.2%) and elevated serum TSH levels (65.6%; P<0.001). Fully adjusted logistic regression models revealed increased odds for carotid plaques (odds ratio (OR) 1.67; 95% confidence interval (CI) 1.11-2.51; P<0.05) as well as for prevalent strokes (OR 1.98; 95% CI 1.05-3.73; P<0.05) in subjects with decreased serum TSH levels, while there was no association between elevated serum TSH levels and carotid plaques or stroke respectively.
CONCLUSIONS: Thyroid function was associated with the presence of carotid artery plaques and prevalent strokes in this population-based sample. Periodical screening and early treatment of atherosclerotic risk factors should be performed in subjects with decreased serum TSH levels.