Context: Prevalence estimates and evidence informing treatment targets for thyroid dysfunction largely come from studies of middle-aged adults. There are limited data on the prevalence of thyroid dysfunction in older populations.
Objective: To determine the prevalence of thyroid dysfunction and risk factors for abnormal thyroid tests in older adults.
Methods: We conducted a cross-sectional analysis of data from participants aged 65 or older in the Atherosclerosis Risk in Communities (ARIC) study who attended visit 5 in 2011-2013. We measured serum concentrations of triiodothyronine (T3), free thyroxine (FT4), thyroid peroxidase antibody (Anti-TPO), and thyroid stimulating hormone (TSH) in 5,392 participants. We used multivariable linear and logistic regression to assess associations of demographic and clinical risk factors with thyroid hormone levels.
Results: In this population of older adults (mean age 76; 56% women and 22% black), the prevalence of thyroid dysfunction was up to 25% when accounting for treated and untreated thyroid dysfunction categories. 15.6% reported use of medication for thyroid dysfunction. Among those not being treated, the prevalence of overt chemical hypothyroidism was 6.0% and subclinical hypothyroidism was 0.82%. Overt chemical hyperthyroidism and subclinical hyperthyroidism affected 0.26% and 0.78% of the population, respectively. Multivariable adjusted cardiovascular risk factor associations for TSH, FT4 and T3 levels are presented in Table. Men were less likely to be anti-TPO positive compared to women (OR=0.59, CI: 0.47,0.75, P<0.001).
Conclusions: There is a high prevalence of thyroid dysfunction in this older, community-based population. Prevalence of thyroid dysfunction and thyroid hormone levels vary with sex, race, age group and multiple cardiovascular risk factors. Accounting for these associations in the clinical setting might prove useful in improving thyroid function assessment in this age group.