Abstract
Among euthyroid individuals, having an anti-thyroid peroxidase antibody (TPO-Ab) titer in the normal range (negative) is positively associated with atherosclerosis as evaluated based on carotid intima-media thickness (CIMT). Atherosclerosis is an established risk factor for cardiovascular disease, but no significant association between yearly progression in CIMT and cardiovascular disease has been reported. Therefore, clarifying the association between having a TPO-Ab titer in the normal range and yearly progression in CIMT (i.e., active arterial wall thickening) among euthyroid individuals could help inform strategies for preventing cardiovascular disease. We conducted a prospective study of 1069 Japanese subjects with free triiodothyronine and free thyroxine levels within the normal range. Having a TPO-Ab titer in the normal range was significantly positively associated with baseline atherosclerosis and significantly inversely associated with active arterial wall thickening. After adjusting for known confounding factors, the adjusted odds ratio (OR) and 95% confidence interval (CI) of log (TPO-Ab titer) for baseline atherosclerosis and active arterial wall thickening was 2.16 (1.07, 4.35) and 0.59 (0.37, 0.93), respectively. Since progression in CIMT is a process of aggressive endothelial repair, deficient endothelial repair inhibits active arterial wall thickening. Therefore, high–normal TPO-Ab titers might induce a deficiency in endothelial repair.
Highlights
Thyroid function could influence the association between thyroid peroxidase antibody (TPO-Ab) and the progression of atherosclerosis evaluated by carotid intima-media thickness (CIMT)
We hypothesized that having a TPO-Ab titer in the normal range is positively associated with baseline atherosclerosis and inversely associated with active arterial wall thickening among euthyroid individuals
Among the present study population (n = 1069), 107 (10.0%) participants were diagnosed as having atherosclerosis at baseline, and 433 (40.5%) were found to have active arterial wall thickening during follow-up
Summary
A previous study with three years follow-up of rheumatoid arthritis patients reported a larger carotid intima-media thickness (CIMT) progression in patients TPO-Ab positive than in those TPO-Ab negative. This study found that TSH levels were higher in TPO-Ab positive patients than in TPO-Ab negative patients [1]. Subclinical hypothyroidism, defined as increased serum thyroid-stimulating hormone (TSH) concentrations and normal serum free thyroxine levels (free T4), is reported to be positively associated with carotid atherosclerosis [2]. Our previous cross-sectional study found a significant positive association between normal TPO-Ab titers (negative) and carotid atherosclerosis (CIMT ≥ 1.1 mm) among euthyroid individuals, defined as having free triiodothyronine (free T3), free T4, and TSH levels with the normal range [3]. Independent of thyroid function, high–normal TPO-Ab titers might lead to the development of carotid atherosclerosis
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