Journal reference: Rondondi N, den Elzen WPJ, Bauer DC, et al. Subclinical hypothyroidism and the risk of coronary heart disease and mortality. JAMA. 2010;304(12):1365-1374 
|Subclinical hypothyroidism (elevated TSH with normal thyroxine levels) is associated with increased risk of coronary heart disease (CHD) events and mortality.
It is reasonable that asymptomatic subclinical hypothyroidism with minimal increases of TSH up to 6.9 mIU/L not require treatment with thyroxine. However, testing for thyroid antibodies and TSH monitoring is recommended to detect conversion to overt hypothyroidism.