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Thyroid function changes and cardiovascular health in older people

There should be a higher threshold for treating thyroid problems in older people, studies suggest

There should be a higher threshold for treating thyroid problems in older people, studies suggest

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Thyroid hormones have significant effects on the cardiovascular system. In general, high levels of thyroid hormones, or hyperthyroidism, are associated with an increased risk of altered heart rhythms, such as atrial fibrillation.

The reduced levels of thyroid hormone found in hypothyroidism may cause atherosclerosis. Recent large studies have sought to identify age-associated changes in thyroid function and their relevance to cardiovascular mortality in older people.

Thyroid function is best assessed by measuring thyroid-stimulating hormone (TSH). When there are reduced levels of the thyroid hormone thyroxine in the blood, TSH levels rise. The emerging pattern suggests that thyroid function normally decreases in older people, leading to slightly raised TSH levels. However, the incidence of mild hyperthyroidism also increases in later life.

More research needed

Large observational studies suggest that mild hypothyroidism, which can be harmful in younger people, tends to be less damaging in those who are older. At the same time the harm from slightly raised levels of thyroid hormone becomes more significant.

A markedly increased risk of atrial fibrillation is a well-known consequence of subclinical hyperthyroidism in patients in the sixth decade of life and beyond.

More research is needed but these observational studies suggest that there should be a higher threshold for treating subclinical hypothyroidism and subclinical hyperthyroidism in older people. In other words, slightly raised TSH levels that indicate reduced thyroxine and so hypothyroidism can be tolerated in older people. Low levels of TSH should be treated promptly to avoid hyperthyroidism.

Ruth Sander is an independent consultant in the care of older people

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