Oxidative stress parameters in serum and low density lipoproteins of Hashimoto's thyroiditis patients with subclinical and overt hypothyroidism

Although prooxidant and antioxidant status were reported to be changed in clinical and experimental hypothyroidism, obtained results are conflicting. In addition, in subclinical hypothyroidism, scarced and controversial data are available about oxidative stress. Therefore, we aimed to investigate prooxidant–antioxidant status only in Hashimoto's thyroiditis (HT) patients with subclinical (sHT) and overt hypothyroidism (oHT). Thirty sHT and 18 oHT patients and 30 healthy control subjects were included in the study. Endogenous and prooxidant 2,2′-azobis-(2-amidinopropane) hydrochloride (AAPH)-induced malondialdehyde (MDA), diene conjugate (DC), protein carbonyl (PC) and nitrotyrosine (NT) levels as well as ferric reducing antioxidant power (FRAP) were determined in serum. In addition, endogenous DC and copper-induced MDA levels were measured in low density lipoprotein (LDL) fraction. Although there were no significant difference in serum endogenous MDA and DC levels, AAPH-induced MDA levels were significantly increased in sHT patients. All these parameters increased in oHT patients. Serum PC levels were detected to be increased in both sHT and oHT patients. Serum FRAP values did not alter in sHT patients, but they lowered in oHT patients. Endogenous DC and copper-induced MDA levels in LDL fraction did not change in sHT patients. However, these parameters were detected to be increased significantly in oHT patients as compared to controls and sHT patients. In conclusion, there were significant increases in oxidative stress parameters in serum and LDL-fraction in oHT patients. However, oxidative stress was detected to stimulate partly in serum, but not LDL fraction in sHT patients. ► Serum indices of oxidative stress and LDL oxidizability in patients with sHT and oHT were evaluated. ► Serum MDA, DC, AAPH-induced MDA, PC, NT, FRAP and LDL oxidizability were measured. ► Serum AAPH-induced MDA and PC levels were increased in patients with sHT. ► Oxidative stress parameters increased in serum and LDL-fraction in oHT patients.