How are TSH and longevity related?

TSH and longevity have a complex, U-shaped relationship. Both very high and very low TSH levels are associated with increased mortality. Some observational studies suggest that slightly elevated TSH (subclinical hypothyroidism) may be linked to longer lifespan, possibly due to reduced metabolic rate and lower oxidative stress. However, this association is not causal and is confounded by age, sex, and health status. Thyroid hormones regulate heart rate, metabolism, and bone density; overt hyper- or hypothyroidism should be treated. Genetic variants in TSH receptor or thyroid function genes have only small effects on TSH levels. There is no robust evidence that deliberately manipulating TSH extends lifespan. Do not attempt to alter your TSH without medical supervision. The evidence is based on population studies and is moderate in strength.