Thyroid Function Changes in the Elderly and Their Relationship to Cardiovascular Health: A Mini-Review

Abstract

Background: Thyroid hormones have significant effects on the cardiovascular systems. In general, hyperthyroidism is associated with an increased risk of dysrhythmias, while hypothyroidism may cause atherosclerosis. Recent large studies have sought to identify aging-associated changes in thyroid function and their relevance to cardiovascular morbidity and mortality in the elderly. Conflicting results have often been published, likely due to the heterogeneity of the studied populations. Objective: This review seeks to briefly summarize the most recent large population studies analyzing thyroid changes with aging and interpreting their effects on cardiovascular health in the elderly. Methods: Selective review of recent literature. Results: The emerging pattern suggests a slight decrease in thyroid function in the elderly leading to slightly higher thyroid stimulating hormone (TSH) levels. However, the incidence of mild hyperthyroidism also increases, especially in populations with historical or current iodine deficiency. Large observational studies suggest that the potential harm from mild hypothyroidism seen in younger population tends to diminish in older subjects, while the harm from mild hyperthyroidism becomes more significant. A markedly increased risk of atrial fibrillation is a well-established consequence of subclinical hyperthyroidism in patients in the sixth decade of life and beyond. Conclusions: The absence of large prospective interventional data does not allow the formulation of strict clinical recommendations, but a higher TSH threshold for treating both subclinical hypothyroidism and subclinical hyperthyroidism in the elderly seems reasonable.