Abstract
Background/Objectives: Hashimoto thyroiditis (HT) is an autoimmune disease affecting the thyroid, often leading to hypothyroidism, even in individuals with adequate iodine intake. Despite achieving biochemical euthyroidism through levothyroxine (LT4) therapy, many patients continue to experience persistent symptoms, likely due to ongoing thyroid autoimmunity. Photobiomodulation (PBM) has shown promise in treating autoimmune conditions, but its effect on thyroid volume (TV) remains unclear. This study aimed to assess the efficacy of PBM combined with supplements in restoring thyroid function and normalising TV compared to the use of supplements alone. Methods: Ninety-eight females aged 20-50 years old were divided into two groups: Group 1 received PBM and supplements and Group 2 received supplements only. The PBM parameters were as follows: 820 nm wavelength, 200 mW power, continuous mode, 20 s per point at 8 points (32 J/cm(2) per point), twice weekly for three weeks. Both groups received vitamin D3 supplementation (if serum < 40 ng/dL) and 100 µg of oral selenium daily. Results: Ninety-seven participants completed the study (51 in Group 1, 46 in Group 2). Group 1 showed significantly greater improvements in TV normalisation and weight loss and reductions in BMI, waist/hip circumference, waist-to-hip ratio, TSH, anti-TPO, anti-TG, and LT4 dosage (p < 0.05). Conclusions: This study demonstrates that low-fluence PBM combined with supplements can effectively improve thyroid function, reduce TV, and enhance anthropometric and clinical outcomes in HT patients. The protocol holds potential for broader application and further validation in larger trials.