Subclinical hypothyroidism — an unexpected ally in the fight against sarcopenia

BACKGROUND: Thyroid hormones are essential for maintaining metabolism involved in regulating growth and development. Skeletal muscles are their primary target organ, and thyroid hormone signaling plays a role in the development, plasticity, and regeneration of skeletal muscles. Conditions such as hypo- and hyperthyroidism negatively affect the state of this tissue. However, in our earlier studies, bigger volume of thigh muscle was found to be one of the factors associated with lower mortality in individuals with high levels of thyroid-stimulating hormone.

AIM: To evaluate the impact of function thyroid gland on the risk of decreased volume of thigh muscles in older adults.

MATERIALS AND METHODS: This study was carried out on the basis of the second examination of the Crystal study of community-dwelling individuals 65+ (n = 383). The main study parameters involved thyroid-stimulating hormone, thigh muscle volume, complete blood count test, CRP, comprehensive geriatric assessment, non-communicable chronic diseases.

RESULTS: Compared with the participants with thyroid-stimulating hormone levels between 3.3 and 10.0 mIU/L, the participants with thyroid-stimulating hormone levels <0.2 mIU/L and the participants with thyroid-stimulating hormone levels between 0.2 and 3.2 mIU/L had lower body mass index, thigh muscle volume and the high prevalence of autonomy decline (p < 0.05). Even after adjusting for sex, age, malnutrition, body mass index, and autonomy decline, high thyroid-stimulating hormone levels were associated with bigger thigh muscle volume, with an odds ratio (95% confidence interval) of 3.274 (1.111–9.647).

CONCLUSIONS: The thyroid-stimulating hormone levels from 3.3 to 10.0 mIU/L increases the chances of maintaining bigger thigh muscle volume in older adults by 3.3 times.