Associations between the levels of thyroid hormones and abdominal obesity in euthyroid post-menopausal women.

Background: The aim of this study was to explore the association between thyroid hormones and abdominal fat quantities in euthyroid post-menopausal women.

Methods: Serum levels of thyroid stimulating hormone (TSH), free triiodothyronine (fT3), and free thyroxine (fT4) as well as body mass index (BMI) and waist circumference (WC) were collected from 540 euthyroid post menopausal women aged 45-65 years. Magnetic resonance imaging (MRI) was performed to measure visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) area. Multivariate linear regression analysis was used to determine whether abdominal fat was associated with thyroid hormones.

Results: Weight, BMI, WC, fasting plasma glucose (FPG), fasting insulin (Fins), homeostasis model assessment of insulin resistance (HOMA-IR), low-density lipoprotein cholesterol (LDL-C), triglyceride (TG), TSH, and fT4 were higher in the obese group than in the nonobese group (p < 0.05). The study participants were divided into four groups according to quartiles in the light of TSH reference range (0.1-4.2 mU/L). Subcutaneous adipose tissue and VAT increased with the TSH levels. Adjusted for age, years since menopause (YSM), BMI, and HOMA-IR, VAT was negatively correlated with fT4 and positively correlated with fT3 and fT3-to-fT4 ratio (fT3/fT4) (p < 0.05), while no association was found between SAT and thyroid hormones. Similarly, we found no relation between body fat distribution and TSH. Furthermore, the association of common indicators of obesity and thyroid hormones showed no significance.

Conclusions: In euthyroid post-menopausal women, VAT rather than SAT was negatively correlated with fT4, and positively correlated with fT3 and fT3/fT4.