TT3, a More Practical Indicator for Evaluating the Relationship Between Sarcopenia and Thyroid Hormone in the...

Area of Science:

• Gerontology
• Endocrinology
• Muscle Physiology

Background:

• Sarcopenia is a prevalent age-related condition.
• Thyroid hormones (THs) may play a role in sarcopenia pathogenesis, but previous findings are inconsistent.
• This study investigates THs and sarcopenia in Chinese elderly euthyroid individuals.

Purpose of the Study:

• To examine the association between thyroid hormones and sarcopenia in elderly euthyroid Chinese.
• To identify specific thyroid hormone indicators relevant to sarcopenia in this population.

Main Methods:

• 309 elderly euthyroid subjects (average age 85.19 years) were assessed.
• Participants were categorized into four groups based on sarcopenia severity (AWGS 2019 criteria).
• Serum thyroid hormone levels (TT3, FT3, TT4, FT4, TSH, rT3, TBG), muscle mass, hand grip strength (HG), and gait speed (GS) were measured.

Main Results:

• Sarcopenia group showed higher age and FRAIL scores, with significantly lower FT3 and TT3 levels.
• Partial correlation revealed positive associations of FT3, TT3, and TSH with HG, and TT3 with GS.
• Multivariate regression indicated TT3 is positively linked to muscle strength and negatively to sarcopenia risk.

Conclusions:

• A significant association exists between low total triiodothyronine (TT3) levels and sarcopenia.
• Maintaining higher TT3 concentrations within the normal range may be beneficial for managing sarcopenia in the elderly.
• TT3 is a more stable and practical indicator than FT3 for evaluating thyroid hormone-sarcopenia relationships in euthyroid elderly.