Triiodothyronine level predicts visceral obesity and atherosclerosis in euthyroid, overweight and obese subjects: T3 and visceral obesity

Objective: We assessed how thyroid hormones affect the visceral obesity and atherosclerosis in euthyroid, overweight and obese Asian subjects. Methods: Metabolic parameters and thyroid hormone levels were measured in 177 subjects who visited obesity clinic at Gangnam Severance Hospital. Total adipose tissue area (TAT), subcutaneous adipose tissue area (SAT), visceral adipose tissue area (VAT) were quantified by computerized tomography scan, and, pulse wave velocity (PWV) was measured as a marker of atherosclerosis. Results: T3 was significantly related to all the measures of abdominal fat, TAT (P= 0.001), SAT (P = 0.015), VAT (P< 0.001), and waist circumference (P = 0.001) as well as BMI (P = 0.017) and total body fat percent (P= 0.001) after adjusting for age and sex. In multiple regression analysis, T3 was independently associated with VAT (̌ =0.486, P= 0.009). There was a positive correlation between T3 and PWV. Conclusions: T3 level is positively associated with the amount of visceral fat and PWV. Visceral obesity seems to cause an increase in circulating T3 level as an adaptational response to increase the energy expenditure, and thus a more close attention and an effort to assess cardiovascular risks should be made to people with high normal T3 level.