Subclinical hypothyroidism: To treat or not to treat?

Subclinical hypothyroidism affects 4.3% of the US population. Despite this prevalence, whether to treat or to observe patients with subclinical hypothyroidism remains controversial. Guidelines for overt hypothyroidism strongly favor treatment for symptomatic benefits, but the same benefits of levothyroxine treatment have not been proven for patients with subclinical hypothyroidism-most likely due to the asymptomatic nature of the condition. Additionally, a connection between subclinical hypothyroidism and cardiovascular complications has not been definitively established, although the evidence favors a relationship. This article describes the background, presentation, and diagnostics of subclinical hypothyroidism, treatment, and potential cardiovascular complications, so clinicians can decide if initiating treatment is best for their patients with subclinical hypothyroidism.