Mild subclinical hypothyroidism may delay decline in functional mobility in elderly individuals, according to findings from Eleanor Simonsick and colleagues as part of the Health, Ageing and Body Composition study. “Our findings, taken together with other work conducted exclusively on older adults, call for development of age-specific cut-off points defining treatment guidelines for subclinical hypothyroidism,” says Simonsick.

The researchers measured the TSH levels of 2,290 participants aged 70–79 years with no apparent mobility limitations, and categorized them as either euthyroid, mild subclinical hypothyroid or moderate subclinical hypothyroid, according to US Preventive Services Task Force criteria.

The investigators found that functional mobility, as assessed with both self-reported and performance-based measures, was similar among individuals classified as euthyroid and those with moderate subclinical hypothyroidism. However, participants with mild subclinical hypothyroidism (but normal levels of free T4) demonstrated better mobility, increased walking ease and were more likely to have good cardiorespiratory fitness than individuals with normal thyroid function.

Simonsick and co-workers also identified a positive association between mild subclinical hypothyroidism and mobility, as defined by gait speed. Furthermore, at 2–4 years of follow-up, individuals with mild subclinical hypothyroidism retained a slight functional mobility advantage.

“We next plan to examine whether the relationships found between TSH and mobility in older adults extend to other functional domains, such as strength and cognition,” says Simonsick. They also intend to “evaluate the role of treatment of subclinical hypothyroidism in older adults to determine whether it improves, diminishes or has no impact on functional mobility”.