Is TSH useful for longevity?

TSH (thyroid-stimulating hormone) is a well-established marker of thyroid function. Optimal thyroid function is important for metabolism, energy balance, and cellular health—all factors linked to aging. However, there are no robust longitudinal studies directly validating TSH as a standalone longevity biomarker. The evidence is largely mechanistic and associative: both subclinical hyper- and hypothyroidism have been associated with increased mortality, but the optimal TSH range for longevity remains unclear. Furthermore, TSH reference ranges vary by age, sex, and ethnicity. A single TSH value without T3/T4 and antibodies has limited interpretability. Consumer tests offering TSH should be viewed critically: they often measure a single point value influenced by time of day, diet, and stress. For meaningful assessment of thyroid function in the context of aging, medical follow-up and additional parameters are necessary. In summary, TSH is a useful but insufficient indicator; evidence for a direct role in longevity is weak.