Objective: The relationship between thyroid function and carotid artery stenosis in euthyroid patients is controversial. Therefore, we aimed at evaluating the relationship between the severity of carotid artery disease (CAD) and thyroid-stimulating hormone (TSH) levels in euthyroid patients.
Patients and methods: A total of 90 euthyroid patients with CAD were trichotomized into three groups based on CAD severity. Group 1 comprised patients who had one internal carotid artery with total stenosis and the other with more than 50% stenosis. In Group 2, patients had one internal carotid artery with total stenosis and the other with less than 50% stenosis. Group 3 comprised patients with less than 50% stenosis in both internal carotid arteries. Demographic data, complete blood count, biochemical parameters, and thyroid function parameters were compared between the groups.
Results: No significant relationship was noted between the severity of CAD and demographic data and comorbidity rates. A comparison of the biochemical parameters revealed that TSH levels were significantly different between the groups. Post-hoc analysis showed that Group 1 and Group 3 differed significantly with respect to TSH levels (0.75 ± 0.37 IU/mL vs. 1.39 ± 1.00 IU/mL, p=0.002). A cut-off value of 0.65 yielded 46.67% sensitivity and 81.67% specificity, whereas a cut-off value of 0.70 yielded 53.33% sensitivity and 75.00% specificity. The area under the curve was 0.691 (95% CI, 0.576-0.806) (p=0.003).
Conclusions: TSH can be demonstrated to predict severe carotid artery disease. Therefore, the severity of CAD can be assessed using TSH levels.