Effects of statins on thyroid morphology autoimmunity and functions

Statins are potent inhibitors of the rate limiting step of cholesterol biosynthesis by inhibiting HMG-Co A reductase. In clinical trials, statins are beneficial in the primary and secondary prevention of coronary heart disease. Statins have beneficial effects called pleiotropic effects in different organs and systems other than changes in lipid levels. In this study we aimed to observe antiproliferative pleiotropic effects of statins on thyroid functions, autoimmune markers, thyroid volume and nodularity, as mentioned before in thyroid cell cultures in the literature. After receiving ethic committee approval and a written informed consent was obtained from all subjects, patients risk category and drug requirement is determined by using NCEP ATP III guidelines. One hundred and one subjects were included to the study. In statin group atorvastatin (10-20mg) and rosuvastatin (10-20mg) were given to subjects. There were 69 patients in statin group and 32 in control group. All patients were evaluated for lipid parameters, TSH, anti TPO, anti Tg and thyroid ultrasonography at the outset of therapy and six months later. After six months of therapy there were no changes on TSH, autoimmune markers and thyroid nodule number between statin group and controls. Subjects treated with rosuvastatin 20mg showed lower total thyroid volume as compared with control group and subjects treated with atorvastatin 20mg showed not a difference in total or right lobe volume but there was a significant decrease in left lobe volume (p<0.05).There was a significant reduction in maximum nodule size in rosuvastatin 10mg group (p<0.05). Our results show an association between statin treatment and reduced thyroid volume and maximum nodule diamater in statin subgroups. These results may be explained by antiproliferative effects of statin therapy on thyroid gland. Key words: Hyperlipidemia, HMG-CoA reductase inhibitors, thyroid volume, nodule