A new study published in Journal of the American Geriatrics Society investigated the association of subclinical thyroid disease and thyroid hormone levels with sarcopenia and its defining components in community-dwelling middle-aged and older adults without overt thyroid dysfunction.

In this cross-sectional study, active and retired employees were recruited from public institutions located in six Brazilian cities—6 974 participants from the ELSA-Brasil studys second wave, aged 50 years and older, without overt thyroid dysfunction.Serum levels of thyrotropin (TSH), free thyroxine, and free triiodothyronine (FT3) were measured and divided in quintiles for the analyses. Participants were classified with euthyroidism, subclinical hypothyroidism, and subclinical hyperthyroidism. Muscle mass and muscle strength were assessed. Sarcopenia was defined according to the Foundation for the National Institutes of Health criteria. Analyses were performed separately for middle-aged and older adults (≥65 y).

The results revealed that the frequencies of sarcopenia, low muscle mass, low muscle strength, subclinical hypothyroidism and subclinical hyperthyroidism were 1.5%, 20.8%, 3.8%, 9.1% and 0.9%, respectively. Subclinical thyroid dysfunction was not associated with sarcopenia and its defining components. Among older adults, TSH had a U-shaped association with sarcopenia and low muscle strength. In addition, FT3 had a negative association with muscle mass in both age strata.

From the findings, it was concluded that subtle thyroid hormone alterations are associated with sarcopenia or its defining components in middle-aged and older adults without overt thyroid dysfunction.

Source: Journal of the American Geriatrics Society. 2020 Mar 13. doi: 10.1111/jgs.16416.