Mortality in a complete 4-year follow up of 85-year-old residents of Leiden, classified by serum level of thyrotropin and thyroxine. - PubMed - NCBI
In the 13% of elderly subjects in Leiden with abnormally high serum TSH levels, the mean annual mortality rate was significantly lower than the mortality rate in the 87% of the elderly patients with normal or low serum TSH. The significance is based on 95% confidence levels of the Poisson distribution. The rate in the group with high TSH levels had 16 deaths in 264 person-years of follow up (FU). The majority with normal or low TSH levels had 193 deaths in 1698 person-years of FU.
[Thyroid function, activities of daily living and survival in extreme old age: the 'Leiden 85-plus Study']. - PubMed - NCBI
At the age of 85, there was no relation between the serum levels of thyroid-stimulating hormone (TSH) or free thyroxine (FT4) and limitations in the activities of daily living, the occurrence of depressive symptoms and cognitive deterioration. Neither was any relationship found during the period of follow-up. A higher TSH-level was associated with a lower mortality, even after correction for the differences in performance and health during the base measurement (mortality risk: 0.77 per SD-increase in TSH; 95% CI: 0.63-0.94). The mortality risk per SD-increase in FT4 was 1.16 (95% CI: 1.04-1.30).
The study has been discussed before in other threads very recently.
They found 67 people aged over 85 with high TSH, they found 491 aged over 85 with low-mid TSH. Then using formulas and blood tests derived that high TSH equals long lifespan. Maybe the study is true but I think the obvious answer is that having over 7 times the amount of over 85's with low-mid TSH seems like it is obvious this correlates with longer lifespan?