The effects of simvastatin and levothyroxine on intima-media thickness of the carotid artery in female normolipemic patients with subclinical hypothyroidism: a prospective, randomized-controlled study.

BACKGROUND: Patients with subclinical hypothyroidism (sHT) have an increased risk of developing atherosclerosis, probably related to dyslipidemia. We compared the effects of levothyroxine (L-T4) versus simvastatin treatment on carotid intima-media thickness (IMT) and lipid profiles in patients with sHT.

METHODS: Forty female patients with newly-diagnosed sHT and 20 age- and-sex matched euthyroid female controls were enrolled. Patients were randomized to receive L-T4 (n = 20) or simvastatin (n = 20) for 8 months. Carotid IMT and the serum concentration of cholesterol were measured at baseline and at the end of the treatment.

RESULTS: Compared with controls, sHT patients had higher IMT values (0.66 +/- 0.16 mm versus 0.54 +/- 0.10 mm, P < 0.001). A significant reduction in serum levels of total and low-density lipoprotein (LDL)-cholesterol, triglycerides and mean IMT was observed in patients randomized to the simvastatin group compared to their baseline values. No correlation was demonstrated between the changes in total or LDL-cholesterol concentration and IMT in the simvastatin group. L-T4 replacement resulted in a significant reduction in IMT but serum lipid levels did not change significantly.

CONCLUSION: 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.