Association between thyroid hormone and pre-sarcopenic obesity in euthyroid population: a prospective cohort study

Objective: We aimed to explore the association between thyroid indicators and pre-sarcopenic obesity, pre-sarcopenia, and visceral obesity in a community-based euthyroid cohort. Methods: A total of 1280 euthyroid residents (42.3% men) aged over 40 years were recruited in 2013-2014 and re-examined in 2015-2016. Thyroid indicators were analyzed. Visceral fat area (VFA) was quantified using magnetic resonance imaging and skeletal muscle mass was calculated by bioelectrical impedance analyzer. Pre-sarcopenic obesity was defined as the coexistence of pre-sarcopenia and visceral obesity. Results: During a mean follow-up of 2.1 years, 127 (14.8%), 156 (21.3%), and 120 (20.1%) participants developed new-onset pre-sarcopenic obesity, pre-sarcopenia, and visceral obesity, respectively. Compared with those with the lowest tertile of baseline serum fT3 levels, participants with the highest tertile had an elevated risk of pre-sarcopenic obesity (risk ratio [RR] 1.82, 95% confidence interval [CI] 1.20-2.76) and pre-sarcopenia (RR 1.49, 95%CI 1.04-2.15). Moreover, per 1 standard deviation increase in serum fT3 levels over 2.1 years was positively associated with incident pre-sarcopenic obesity (RR 1.40, 95%CI 1.28-1.53) and pre-sarcopenia (RR 1.29, 95%CI 1.18-1.40), respectively. Conclusion: Elevated serum fT3 levels were associated with increased risks of pre-sarcopenic obesity and pre-sarcopenia in euthyroid Chinese participants.