The obtained results indicate that the effect of metformin on hypothalamic-pituitary-thyroid axis activity is partially related to thyroid function. Metformin treatment may bring clinical benefits to patients with amiodarone-induced hypothyroidism and poor tolerance of exogenous L-thyroxine.

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Background Vitamin D is suggested to reduce cardiovascular risk. Hypothesis Circulating levels of plasma lipids and other cardiovascular risk factors may differ between statin‐treated patients with different vitamin D status. Methods We studied 3 age‐ and weight‐matched groups of men with elevated low‐density lipoprotein cholesterol (LDL‐C) levels: vitamin D–naïve men with vitamin D insufficiency (group A, n = 18), men with vitamin D deficiency/insufficiency effectively treated with vitamin D preparations (group B, n = 16), and vitamin D–naïve men with normal vitamin D status (group C, n = 16). All patients were then treated with atorvastatin (20 mg daily) for 4 months. Plasma lipids, glucose homeostasis markers, and plasma levels of uric acid, high‐sensitivity C‐reactive protein (hsCRP), homocysteine, and fibrinogen were assessed before and at the end of atorvastatin therapy. Results Study groups did not differ in baseline levels of plasma lipids. Men with vitamin D deficiency or insufficiency effectively treated with vitamin D preparations were characterized by decreased insulin sensitivity and higher circulating levels of hsCRP, homocysteine, and fibrinogen in comparison with the remaining groups of patients. Although atorvastatin decreased plasma levels of total cholesterol and LDL‐C to a similar extent in all study groups, its effect on uric acid, hsCRP, homocysteine, and fibrinogen was more pronounced in patients from groups B and C than in men from group A. Moreover, in patients with vitamin D insufficiency, atorvastatin impaired insulin sensitivity. Conclusions The obtained results indicate that the strength of pleiotropic effects of atorvastatin depends on vitamin D status.