Relationship of HDL-related myeloperoxidase (MPO) and paraoxonase 1 (PON1) with coronary artery disease in hashimoto's thyroiditis

Hashimoto's thyroiditis (HT) is an autoimmune disease of the thyroid gland. Free radicals have been reported to be responsible for the complications observed in the pathogenesis of thyroid diseases and in the later stages of the disease. Myeloperoxidase (MPO), which is released during inflammation is an oxidative enzyme present in phagocytes. MPO could be a key element responsible for oxidative damage in the artery wall. Paraoxonase-1 (PON-1), which is one of the molecules that play a role in oxidant balance, is an enzyme that has the role of inhibiting lipoprotein oxidation by hydrolyzing lipid peroxides in oxidized low density lipoprotein (LDL) structure. We investigated the role of HDL-associated MPO and PON-1 in patients with HT in terms of coronary artery disease. Our study group consisted of 54 patients with Hashimato diagnosis and 28 healty individuals as control group. MPO and PON-1 levels were determined spectrophotometrically. HDL levels were determined on the auto analyzer. When the study groups were evaluated, MPO levels were significantly higher in patients with hashimato thyroiditis than the control group (p<0,05 p=0,001). A negative correlation was obtained between MPO and PON-1 (r=-0,685). HDL levels were lower in HT patients than in the control group (p˃0,05 p=0,781). The decrease in PON-1 activity and increase in MPO activity due to hypothyroid effect increases lipid peroxide formation and accelerates oxidized LDL formation, which leads to decrease in antioxidant capacity and development of atherosclerosis. Since oxidative stress in thyroid diseases is also responsible for the complications observed in the later stages of the disease, we think that important data were obtained with this study in terms of both diagnosis and treatment.