Mild thyroid hormone excess is associated with a decreased physical function in elderly men

Area of Science:

• Gerontology
• Endocrinology
• Musculoskeletal Health

Background:

• Subclinical hyperthyroidism (Shyper) may impact skeletal muscle mass and strength in adults.
• The effects of Shyper on physical function in the elderly population remain largely unknown.
• This study investigates the association between mild thyroid hormone excess and physical performance in older individuals.

Purpose of the Study:

• To explore the relationship between subclinical hyperthyroidism and physical function in a population-based sample of older persons.
• To determine if mild thyroid hormone excess is associated with reduced physical performance in elderly men and women.
• To assess the predictive value of thyroid hormones on physical function decline over time.

Main Methods:

• Cross-sectional analysis comparing calf muscle cross-sectional area (CMA), handgrip strength, nerve conduction velocity (NCV), and Short Physical Performance Battery (SPPB) scores between euthyroid (Eut) and Shyper individuals.
• Longitudinal analysis evaluating the relationship between baseline thyroid-stimulating hormone (TSH), free triiodothyronine (FT3), and free thyroxine (FT4) and the 3-year change in SPPB score.
• Inclusion of 364 Eut and 28 Shyper men, and 502 Eut and 39 Shyper women in cross-sectional analysis; 304 men and 409 women in longitudinal analysis.

Main Results:

• Shyper men exhibited significantly lower SPPB scores compared to euthyroid controls (p = 0.02), with increased likelihood of poor physical performance (OR = 2.97, p < 0.05).
• No significant differences in CMA, grip strength, or NCV were observed between euthyroid and Shyper men.
• In euthyroid men, higher baseline FT4 levels significantly predicted lower SPPB scores at the 3-year follow-up (p = 0.02).

Conclusions:

• Mild thyroid hormone excess, even in subclinical hyperthyroidism, is associated with reduced physical function in elderly men.
• The findings suggest that monitoring thyroid function may be important for maintaining physical performance in older men.
• Further research is warranted to elucidate the mechanisms underlying the association between thyroid hormone excess and physical decline in the elderly.