TT3, a More Practical Indicator for Evaluating the Relationship Between Sarcopenia and Thyroid Hormone in the Euthyroid Elderly Compared with FT3

Jihai Chen; Lijun Wei; Xiaoxia Zhu; Wenli Xu; Yuxin Zou; Xinyu Qi; Jia Fang; Xiaodong Wang; Xiaolan Shi; Yunlu Sheng; Guoxian Ding; Xiaojun Ouyang; Yu Duan

doi:10.2147/CIA.S420558

TT3, a More Practical Indicator for Evaluating the Relationship Between Sarcopenia and Thyroid Hormone in the Euthyroid Elderly Compared with FT3

Clin Interv Aging. 2023 Aug 4:18:1285-1293. doi: 10.2147/CIA.S420558. eCollection 2023.

Authors

Jihai Chen^{1

2}, Lijun Wei², Xiaoxia Zhu², Wenli Xu², Yuxin Zou², Xinyu Qi², Jia Fang², Xiaodong Wang², Xiaolan Shi¹, Yunlu Sheng², Guoxian Ding², Xiaojun Ouyang¹, Yu Duan²

Affiliations

¹ Department of Geriatric, Geriatric Hospital of Nanjing Medical University, Nanjing, 210024, People's Republic of China.
² Department of Geriatric Endocrinology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, People's Republic of China.

Abstract

Background and aims: Sarcopenia is a common disease in the elderly, and the thyroid hormone (TH) might participate in the pathogenesis of sarcopenia. However, the results of previous studies were not completely consistent. We performed this study to investigate the association between THs and sarcopenia in a Chinese elderly euthyroid population.

Subjects and methods: A total of 309 Chinese elderly euthyroid subjects with an average age of 85.19 ± 7.8 years were enrolled. Participants were divided into four groups (non-sarcopenia, possible sarcopenia, sarcopenia and serve sarcopenia) according to the consensus update of AWGS in 2019. Serum levels of TT3, FT3, TT4, FT4, TSH, rT3 and TBG were measured. Muscle mass was measured by multifrequency bioelectrical impedance analysis, hand grip (HG) was represented by spring-type dynamometer, and gait speed (GS) was determined by 6-metre walk test. The FRAIL scale was used to assess frailty.

Results: Compared to the non-sarcopenia group, the sarcopenia group showed a significant increase in age and FRIAL score, while FT3 and TT3 levels decreased significantly. Partial correlation analysis (adjusted by age, gender and the scores of FRIAL scale) indicated that FT3, TT3 and TSH had significant positive correlations with HG, and there also was a significant positive correlation between TT3 and GS. In addition, after adjusting for age, gender, BMI, ALT, sCr, and score on the FRAIL scale, the multivariate linear regression analysis showed that TT3 was positively associated with muscle strength and negatively associated with sarcopenia risk.

Conclusion: There is an association between the low TT3 level and sarcopenia. Therefore, maintaining higher T3 concentrations within the normal range appears to be beneficial for sarcopenia in the elderly. In addition, due to the fluctuation of FT3, TT3 is a more stable and practical indicator to evaluate the relationship between sarcopenia and thyroid hormone in the elderly euthyroid population.

Keywords: elderly; muscle strength; sarcopenia; thyroid hormone.

MeSH terms

Aged
Aged, 80 and over
Hand Strength*
Humans
Muscle Strength
Sarcopenia* / epidemiology
Thyroid Hormones
Thyrotropin

Substances

Thyroid Hormones
Thyrotropin

Grants and funding

This work was supported by National Natural Science Foundation of China (No. 81670724, 82071582) and Jiangsu Health Commission Foundation of China (No. BJ19029, LKM2022011).