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 ≥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.