Zhao T, et al. - The impact of L-T4 therapy on endothelial function as ascertained by C-IMT in patients with subclinical hypothyroidism (SCH) was assessed in this study. This meta-analysis shows that L-T4 treatment of SCH patients can decrease C-IMT, possibly as a result of the reduction of total cholesterol, triglyceride, low-density lipoprotein, systolic blood pressure, diastolic blood pressure, lipoprotein(a), and flow-mediated dilatation. Reduced C-IMT was seen in SCH patients after long-term (>6 months) L-T4 treatment. RCTs with larger samples are needed to confirm these observations.