What thyroid conditions are more prevalent with aging?
Thyroid nodules increase with age, with an estimated prevalence of 37% to 57% in the elderly population. The risk of malignancy in a nodule also increases with age, however the prevalence of thyroid cancer is not necessarily higher in adults over age 60 depending on the population studied.
The most frequent cause of hyperthyroidism in older adults is toxic multinodular goiter rather than Graves’ disease. Presenting symptoms of hyperthyroidism may be more atypical, with apathetic symptoms being more common in older adults.
Hypothyroidism increases significantly with age as a result of multiple conditions, including autoimmune thyroid disorders and the use of medications that can impair thyroid function. The incidence of myxedema coma is also higher in older adults compared with younger adults.
Subclinical hypothyroidism is defined as having a mildly elevated serum TSH level associated with fT 4 values that are still within the reference range. This condition clearly increases with age, but the actual incidence depends on the definition of the upper normal limit (UNL) for serum TSH. For example, using the common current UNL of 4.5 mIU/L, 15% of disease-free Americans older than 80 years of age have subclinical hypothyroidism. However, if the UNL of the TSH reference range were to change to 2.5 mIU/L, the incidence of subclinical hypothyroidism would be as high as 40%.