Treatment of Subclinical Hypothyroidism Is Associated with Fewer Ischemic Cardiac Events

Subclinical hypothyroidism (serum thyrotropin level, 5.01–10.0 mIU/L, and normal free thyroxine level) has been associated with elevated risk for adverse cardiac events and mortality in middle-aged, but not older, adults. Randomized trials of treating patients with subclinical hypothyroidism have been small and short term, and they have focused on subjective symptoms, not cardiac endpoints. Whether to treat patients with subclinical hypothyroidism has been controversial.

In this retrospective cohort study, U.K. researchers identified 3093 younger patients (age range, 40–70) and 1642 older patients (age, >70) with subclinical hypothyroidism; roughly 50% in each group were treated with levothyroxine (median dose, 75 µg daily). In analyses adju…