Chronic autoimmune thyroiditis (CAT) is the most common cause of hypothyroidism in iodine-replete areas. An autoimmune dysfunction causes humoral and cellular responses that lead progressively to thyroiditis. There is no effective therapy available that can change the natural history of CAT, which presents a high incidence of hypothyroidism and requires continuous treatment with levothyroxine (LT4).~Laser light can be valuable since the local and systemic actions of low-level laser therapy (LLLT) have been shown to be effective in treating autoimmune diseases, such as rheumatoid arthritis and Sjogren's syndrome. There is also evidence suggesting that LLLT can facilitate regeneration of various tissues and, in animal thyroids, can lead to improvement in microcirculation and increases in serum triiodothyronine (T3) and thyroxine (T4) levels. Since the LLLT is a non-invasive, cost-effective and painless procedure, the objective of this randomized clinical trial was to evaluate the effectiveness of LLLT in patients with hypothyroidism caused by chronic autoimmune thyroiditis, based on patients' thyroid function, their concentration of thyroid autoantibodies, and the parameters of their ultrasonography study.
The purpose of this study is to evaluate whether low-level Laser therapy is effective in ameliorating the thyroid function of patients with hypothyroidism caused by chronic autoimmune thyroiditis.