RESUMO
This study aimed to examine the effects of low-level laser therapy (LLLT) combined with levothyroxine replacement therapy on thyroid function, oxidative stress (OS), and quality of life in patients with Hashimoto's thyroiditis (HT). Forty-six patients diagnosed with HT were randomized to receive active LLLT (n = 23) and sham LLLT (n = 23) twice a week for three weeks. Clinical and laboratory evaluations of the participants were performed before treatment and three months after treatment. Biochemical parameters were taken from the patient file requested by the physician as a routine examination. Malondialdehyde and nitricoxide indicating oxidant stress and superoxide dismutase, catalase, and glutathione, which indicate antioxidant capacity, were used in OS evaluation. The Oxidative Stress Index was calculated by measuring the Total Antioxidant Status and the Total Oxidant Status. At the end of our study, a significant improvement in oxidant and antioxidant biomarker levels showing OS and quality of life was observed in the treatment groups (p < 0.05). There was no change in thyroid function and autoimmunity at the end of the treatment between the two groups (p > 0.05). Improvements in glutathione levels and quality of life were significantly higher in the active treatment group than in the sham-controlled group. LLLT was found to be more effective on OS and quality of life in patients with HT than in patients in the sham-controlled group. It was concluded that LLLT is a safe and effective method that can be used in the treatment of patients with HT.