Affiliations: Department of Biochemistry of Cerrahpasa Medical Faculty, University of Istanbul, Turkey | Department of Biophysics of Cerrahpasa Medical Faculty, University of Istanbul, Turkey | Department of Endocrinology Division of Internal Medicine of Cerrahpasa Medical Faculty, University of Istanbul, Turkey
Abstract: Hypothyroidism is associated with atherosclerotic events, however, the mechanism is unclear. We investigated the effects of oxidative stress and cholesterol on plasma viscosity in female patients with hypothyroidism (n=20; mean age: 45.5±5.5 years) at baseline and after L‐thyroxine replacement therapy (average daily dose being 0.1 to 0.15 mg). Two blood samples were taken after 2.3±1.2 months. In hypothyroid state plasma viscosity and thiobarbituric acid reactive substance (TBARS; marker of oxidative stress were significantly higher (p<0.001 and p<0.001), and plasma protein thiol (antioxidants) levels were significantly lower (p<0.001) than in the healthy state (female; n=15). After L‐thyroxine replacement therapy, patients reached to euthyroid state. In this state, the levels of plasma viscosity and TBARS were decreased (p<0.001 and p<0.001), and protein thiol levels were significantly elevated (p<0.001). There was a significant correlation between plasma cholesterol and viscosity (r=0.64, p<0.001), as well as plasma protein thiol (r=−0.59, p<0.001) in the patients. The correlation between viscosity and TBARS was weak (r=0.29, p<0.01). Therefore hypothyroidism may be associated with atherosclerotic process by different mechanisms.
