Relationships of Thyroid Hormones in the Normal Range to Coronary Artery Disease in Different Age Groups

Abstract

Background: The change of thyroid hormones with age may partially explain the effect of age on coronary artery disease (CAD). However, the effects of thyroid hormones within the normal range on CAD in different age were unkown. Aims: To evaluate the relationships between thyroid hormones within the normal range and CAD in different age groups. Methods: 769 individuals were enrolled. Individuals were divided into two groups according to their age: ＜ 60 years and ≥ 60 years. Free triiodothyronine (FT3), free thyroxine (FT4) and thyroid stimulating hormone (TSH)were compared between CAD and non-CAD group. The associations of FT3, FT4 and TSH with CAD in different age groups were evaluated by logistic regression analyses. Results: The levels of FT4 were significantly higher in CAD than non-CAD group of total (13.75 ± 2.46 vs. 12.90 ± 1.58 pmol/l, p = 0.003) and ≥ 60Y (13.83 ± 2.73 vs. 12.69 ± 1.47 pmol/l, p = 0.041). The incidences of CAD were significantly higher in the fourth quartile than the first quartile of FT4 in total (7.2% vs. 2.1%, p = 0.017) and ≥ 60Y (14.5% vs. 4.3%, p = 0.041). FT4was the independent risk factor for CAD in ≥ 60Y and total people by univariate and multivariate analyses (all p ＜ 0.05). No associations were found between FT3, TSH and CAD in different age groups. Conclusions: FT4 within the normal range was associated with CAD in ≥ 60Y and total people, but not FT3 and TSH. The relationship between FT4 within the normal range and CAD may be affected by age.