Thyroid hormones, metabolic syndrome and Vitamin D in middle-aged and older euthyroid subjects: a preliminary study

Aim: To explore the relationship between thyroid hormones, Vitamin D (Vit.D) serum concentrations and metabolic syndrome (MetS) in euthyroid subjects. Methods: 123 community-dwelling subjects were enrolled. According to thyroid-stimulating hormone (TSH) values the sample was divided into: (1) group 1 (TSH ≤ 2 mU/L); (2) group 2 (TSH > 2 mU/L). Results: Group 2 showed higher percentage of subjects with MetS (p = 0.003) and hypertension (p = 0.031), higher values of waist circumference (WC) (p = 0.007), parathyroid hormone (p = 0.016), glycaemia (p = 0.045), triglycerides (p = 0.034) and free T4 (fT4) (p = 0.013). Correlation analysis showed several weak significant correlations: MetS with TSH (r = 0.202, p = 0.031) and fT3 (r = − 0.206, p = 0.028); THS with body mass index (r = 0.187, p = 0.047) and hypertension (r = 0.199, p = 0.034); Vit.D with WC (r = − 0.185, p = 0.04). Conclusions: Our results showed a possible association between thyroid hormones and MetS. Visceral fat and insulin resistance may be an interesting link between Vit.D and TSH levels.