Subclinical Hyperthyroidism Raises Risk for Mortality and Cardiac Events

The results of prospective cohort studies conflict on whether subclinical hyperthyroidism (thyrotropin level <0.45 mIU/L, with normal free thyroxine and triiodothyronine) is associated with elevated incidence of coronary heart disease (CHD) or atrial fibrillation (AF). This meta-analysis combined the results of 10 such studies with 53,000 participants (median age, 59), of whom 2188 (4%) had subclinical hyperthyroidism.

During median follow-up of 9 years, in analyses adjusted for age and sex, the risk for those with subclinical hyperthyroidism compared to those who were euthyroid was increased 24% for overall mortality, 29% for CHD mortality and 68% for incident AF. Risks were even higher in those with thyrotropin levels <0.10 mIU/L, and risk…