2023 年 10 巻 1 号 p. 32-38
Objective: This study aimed to verify whether low-normal range serum thyroid hormone concentration is associated with carotid arteriosclerosis in men as they age.
Methods: This cross-sectional study included 1,087 men with a euthyroid state who had not been treated for or diagnosed with cardiovascular diseases and/or metabolic disorders in a comprehensive medical examination at Hidaka Hospital in Japan. Participants’ weight, blood pressure, plasma glucose, serum lipid profile, free thyroxine (FT4), and thyrotropin were measured and they were interviewed about their smoking habit. Carotid maximum intima–media thickness (max IMT) was determined by ultrasonography.
Results: Max IMT increased with age and began to exceed 1.1 mm, an indicator of the presence of carotid artery plaque, at ≥50 years of age. Serum FT4 concentrations were significantly lower in those with carotid plaque (p=0.001) and, in multivariate logistic regression analysis were independently associated with carotid plaque only in men aged ≥50 years (β=−1.800, p=0.002). Moreover, max IMT was significantly higher in men with serum FT4 concentration values of <0.97 ng/dL than in those with ≥0.97 ng/dL. These differences were not observed in men aged <50 years.
Conclusion: Serum FT4 concentration was independently associated with age-related increases in carotid max IMT in euthyroid Japanese men. A serum FT4 concentration of <0.97 ng/dL in men aged ≥50 years may help determine their risk for early carotid arteriosclerosis.
