Effect of eicosapentaenoic acid ethyl ester on hypothyroid function

Thyroid hormones affect reactions in almost all pathways of lipid metabolis m. It has been reported that plasma free fatty acid (FFA) concentration in hypothyroidism is generally within the normal range. In this study, however , we show that plasma FFA concentration in some hypothyroid patients is hig her than the normal range. Symptoms of thyroid dysfunction in these individ uals were less severe than those of patients with lower plasma FFA concentr ations. From these findings we hypothesized that the change in FFA concentr ation must correlate with thyroid function. Using an animal model, we then examined the effect of highly purified eicosapentaenoic acid ethyl ester (E PA-E), a n-3 polyunsaturated fatty acid derived from fish oil, on thyroid f unction in 1-methyl-2-imidazolethiol (MMI)-induced hypothyroid rats. Oral a dministration of EPA-E inhibited reduction of thyroid hormone levels and th e change of thyroid follicles in MMI-induced hypothyroid rats. These findin gs suggest that FFA may affect thyroid functions and EPA-E may prevent MMI- induced hypothyroidism.