The relationship between oxidative stress and autoimmunity in Hashimoto's thyroiditis

Abstract

Objective: We have aimed to study the relation between Hashimoto's thyroiditis (HT) and thyroid autoantibodies and oxidative stress parameters in euthyroid, subclinical and overt hypothyroid stages. Design and methods: A total of 124 patients were included in the study; 93 of whom were newly diagnosed with HT (31 patients in each of the euthyroid, subclinical hypothyroid and overt hypothyroid subgroups), aged over 18 and had not received any prior treatment and 31 of whom were healthy volunteers. Results: Total oxidant status (TOS) and oxidative stress index (OSI) levels were higher, and total antioxidant status (TAS) and total thiol and arylesterase levels were lower in the overt hypothyroid group compared to other groups. TOS and OSI levels increased, and TAS levels decreased significantly in each phase from euthyroid, subclinical hypothyroid, to overt hypothyroid subgroups among HT patients. There was a negative correlation between TAS, log (paraoxonase1) and paraoxonase1/HDL and anti-thyroid peroxidase and a negative correlation between anti-thyroglobulin and total thiol. It was also determined that overt hypothroidism was an individual predictor that effects all of the oxidative stress parameters, but not total thiol, levels. Conclusion: Our results suggest that oxidative stress increases continuously during the development of subclinical hypothyroidism and overt hypothyroidism in patients with HT. To determine whether this is a cause or result, randomized, controlled trials that study the effect of antioxidant treatment on the development of overt hypothyroidism and its consequences, e.g., increase in total cholesterol levels, may be performed in euthyroid and/or subclinical hypothyroid patients with HT.

The impact of levothyroxine sodium treatment on oxidative stress in Hashimoto’s thyroiditis

“…For instance, Nanda et al (6) reported higher oxidative stress levels in anti-TPO (+) patients with hypothyroid compared with anti-TPO (−) patients with hypothyroid. Three different studies also had reported higher oxidative stress levels in HT compared with healthy controls, supporting our data (4,9,10,16).…”

“…Data from previous studies suggest that oxidative stress level may be increased due to chronic inflammation (3), deficient thyroid hormone levels (4), excessive autoimmune response, or excessive iodine intake (5) in HT. Reports of higher oxidative stress markers in hypothyroid patients with antithyroid peroxidase (anti-TPO) positivity compared with those without (anti-TPO (-)) (6) and increasing oxidative stress levels by the progression of HT from euthyroid to overt hypothyroid stage (7,8,9) also supported previous data. In the light of these studies, it may be suggested that oxidative stress levels may have been increased in hypothyroid stage of HT, where thyroid hormone deficiency is at maximum levels (9).…”

“…Reports of higher oxidative stress markers in hypothyroid patients with antithyroid peroxidase (anti-TPO) positivity compared with those without (anti-TPO (-)) (6) and increasing oxidative stress levels by the progression of HT from euthyroid to overt hypothyroid stage (7,8,9) also supported previous data. In the light of these studies, it may be suggested that oxidative stress levels may have been increased in hypothyroid stage of HT, where thyroid hormone deficiency is at maximum levels (9). Furthermore, higher oxidative stress levels may also be expected in the existence of autoimmunity at hypothyroid stage (6).…”

Evaluation of Paraoxonase1 Polymorphisms in Hypothyroid Patients and Their Relationship with Paraoxonase Activity and Serum Lipids

“…The results of studies conducted on oxidative stress in hypothyroid patients are conflicting. Ateş et al (32) investigated total antioxidant status in euthyroid, subclinical and clinic patients secondary to Hashimoto's thyroiditis, and observed it to be lowered in clinical hypothyroid patients when compared to healthy controls and other groups. However, oxidative stress index and total oxidant status were significantly higher in clinic hy-pothyroid patients than in the other groups and higher in euthyroid and subclinical patients than the controls.…”

Levothyroxine but Not Selenium Increases Endothelial Progenitor Cell Counts in Patients with Hypothyroidism

“…Hypothyroidism, as well as CV diseases like chronic HF, are associated with oxidative stress, in which altered levels of NO, asymmetric dimethyl arginine (ADMA) and glutathione peroxidase enzymes (selenoproteins that remove hydrogen peroxide and harmful lipid hydroperoxides) exacerbate endothelial dysfunction [12,13,14]. Recently, a study demonstrated that oxidative stress is higher in overt hypothyroid patients than in euthyroid or subclinical hypothyroid patients, and the total antioxidant status is lower in overt hypothyroid subjects compared to the other groups [15]. …”