Patients with subclinical hypothyroidism (SCH) have impaired endothelial function probably related to dyslipidemia. The present study compares the effects of simvastatin versus levothyroxine (LT-4) treatment on lipid profile and endothelial function in patients with SCH. Fifty-nine patients with newly diagnosed SCH were enrolled. Patients were randomized into 3 groups to receive no treatment (n = 19), LT-4 (n = 20), or simvastatin (n = 20). We measured endothelium-dependent vasodilation (EDV) and endothelium-independent vasodilation (EIV) at baseline and after 8 months. Serum total cholesterol, triglycerides and LDL-cholesterol were significantly lower following simvastatin. EDV increased significantly in simvastatin treatment group (7.5% +/- 3.3% vs 14.0% +/- 4.5% (P < 0.01). The improvement of EDV correlated with the percent decrease of LDL-cholesterol (rho = 0.68, P < 0.01). Although LT-4 therapy caused a trend towards an increase in EDV compared to baseline, statistical significance was not achieved. EIV remained unchanged in all three groups. Simvastatin but not LT-4 treatment significantly improves EDV of the brachial artery and dyslipidemia in patients with SCH. Improvement in brachial artery endothelial function may be related in part to a hypolipidemic effect of simvastatin treatment.
Our results demonstrate that simvastatin significantly reduces IMT in addition to the significant improvement in serum lipids in female patients with sHT. This reduction of IMT was independent of the decrease in serum cholesterol during simvastatin treatment. Although L-T4 substitution therapy also decreases IMT, it does not appear to significantly improve lipid levels.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.