Thyroid Function and Mortality in Older Men: A Prospective Study

Abstract

CONTEXT: Mild abnormalities of thyroid function have been associated with both beneficial and detrimental effects on mortality. OBJECTIVE: Our objective was to determine the association between continuous TSH as well as categories of thyroid function with total and cause-specific mortality in a cohort of older men. DESIGN, SETTING, AND PARTICIPANTS: Data were analyzed from the Osteoporotic Fractures in Men (MrOS) study, a cohort of community-dwelling U.S. men aged 65 yr and older. A total of 1587 participants randomly selected for thyroid function testing were included in this analysis. TSH and free T4 were measured at baseline, and four categories of thyroid function were defined. (subclinical hyperthyroid; euthyroid; subclinical hypothyroid TSH<10 mIU/liter; and subclinical hypothyroid, TSH≥10 mIU/liter.) MAIN OUTCOME MEASURE: Total mortality, cardiovascular (CV) and cancer deaths were confirmed by review of death certificates. RESULTS: There were 432 deaths over a mean follow-up of 8.3 yr. In fully adjusted models, there was no association between baseline TSH and any death [relative hazard (RH)=1.01 per mIU/liter, 95% confidence interval (CI)=0.95-1.06], CV death (RH=1.05 per mIU/liter, 95% CI 0.96-1.15), or cancer death (RH=0.96 per mIU/liter, 95% CI=0.85-1.07). There was also no statistically significant association between thyroid function category and total or cause-specific mortality, but few men (n=8) had subclinical hypothyroidism with TSH levels of 10 mIU/liter or higher. CONCLUSIONS: A single measurement of thyroid function did not predict total or cause-specific mortality in this cohort. These data support neither a beneficial nor a detrimental effect of subclinical thyroid dysfunction in older men. SUMMARY: Subclinical thyroid dysfunction is not associated with an increased risk of all-cause or CV mortality in older men.