Trunk fat and leg fat in relation to free triiodothyronine in euthyroid postmenopausal women

Background A high level of free triiodothyronine (FT3) within the reference range may be a potential metabolic risk marker. However, the relationship between different fat depots and FT3 has remained unclear. Objective We aimed to explore the relationships between segmental fat distribution and FT3 in euthyroid middle-aged and elderly men and postmenopausal women. Methods A total of 891 subjects (394 men and 497 women) were enrolled. A bioelectrical impedance analyzer was used to measure total, trunk, arm and leg fat mass (FM) and fat percentage (fat%). The leg fat mass to trunk fat mass ratio (LTR) was calculated to evaluate the relative distribution of leg fat compared with that of trunk fat. Thyroid hormones were measured by electrochemical luminescence immunoassay. Results FT3 in men did not change significantly with increases in LTR quartiles, while FT3 in women decreased significantly (P for trend = 0.004). In multivariate linear regression analysis, multiple metabolic and cardiovascular risk factors were adjusted. The LTR was negatively related to FT3 in women (P