Association of Thyroid-Stimulating Hormone with Resting Energy Expenditure in Euthyroid Elderly Subjects: A Cross-Sectional Study

Abstract

Background: Several studies have reported positive correlations between thyroid-stimulating hormone (TSH) and body mass index (BMI) in euthyroid subjects. As impaired thyroid function is known to affect the metabolic rate, this study investigated whether TSH is associated with resting energy expenditure (REE) in euthyroid elderly subjects, independent of age, anthropometric data and body composition. Methods: Cross-sectional data of 77 women (66-96 years, BMI 18-36 kg/m2) and 55 men (66-86 years, BMI 20-39 kg/m2) were analyzed. REE was measured using indirect calorimetry, body composition by bioelectrical impedance analysis and serum TSH using an electrochemiluminescence immunoassay. Results: REE, fat-free mass (FFM) and waist circumference (WC) were significantly lower, whereas TSH and fat mass (FM) were significantly higher in women than in men. In multiple stepwise regression analysis, with age-adjusted REE (REEadj) as the dependent variable and FFM, FM and WC as independent variables, FFM and WC explained 40.7% in women and FFM 32.8% in men of the variability in REEadj. Including TSH in the model led to a significant rise of the adjusted R-squared value in women only, and explained an additional 2.8% of the variability in REEadj. Conclusions: TSH is independently and negatively associated with REE in euthyroid elderly women.