Thyroid paradox in older age

Abstract

BACKGROUND: The thyroid gland plays an important role in our body, influencing almost all metabolic processes in the body throughout life. However, literature data on the effect of decreased thyroid function on mortality in older people is contradictory. AIM: To evaluate the impact of thyroid-stimulating hormone levels on 5-year survival in older adults. MATERIALS AND METHODS: This work was carried out on the basis of the second screening of the Crystal study of community-dwelling individuals 65+ (n = 383). Main study parameters: thyroid-stimulating hormone level, blood test, lipid profile, albumin, total protein, comprehensive geriatric assessment, 5 years of follow-up. RESULTS: A thyroid-stimulating hormone level of 3.3–10.0 mIU/L was associated with a 44.6% reduced risk of all-cause mortality (hazard ratio 0.554; 95% confidence interval 0.307–0.999) at 5 years of follow-up, regardless of the presence of non-communicable diseases and geriatric status. A thyroid-stimulating hormone level more 10.0 mIU/L is not associated with an increased risk of mortality. The lower risk of mortality in patients with high thyroid-stimulating hormone levels may be due to a larger thigh muscle circumference. After adjustment for all covariates used and thyroid-stimulating hormone level, a 1 cm increase in thigh muscle circumference was associated with a 4.5% reduction in the risk of all-cause mortality (hazard ratio 0.955; 95% confidence interval 0.932–0.979). CONCLUSIONS: The lowest risk of all cause-mortality mortality in persons aged 65 years and older is observed with a thyroid-stimulating hormone level of 3.3–10.0 mIU/L. Thyroid-stimulating hormone level more 10.0 mIU/L is not associated with an increased risk of all cause-mortality.