Effects of Low-Level Laser Therapy on the Serum TGF-β1 Concentrations in Individuals with Autoimmune Thyroiditis

Objective: The objective of this study was to evaluate the serum concentration of transforming growth factor-beta 1 (TGF-beta 1) after low-level laser therapy (LLLT) in patients with hypothyroidism resulting from chronic autoimmune thyroiditis (CAT). Background data: Certain data indicate that LLLT is effective in patients with hypothyroidism caused by CAT; however, the mechanisms of action of LLLT in thyroid tissue are unknown. Cytokines could play a role in the response to LLLT. Methods: A randomized, placebo-controlled trial included 43 patients with a history of levothyroxine therapy for CAT-induced hypothyroidism. The patients were randomly assigned to receive either 10 sessions of LLLT (830 nm, 50 mW output power, and 707 J/cm(2) fluence; L group, n = 23) or 10 sessions of a placebo treatment (P group, n = 20) twice a week. Levothyroxine was maintained at the same dose during the entire study period. TGF-beta 1 was measured both pre-intervention and 30 days post-intervention in both groups. The differences were calculated between the TGF-beta 1 values observed 30 days post-intervention and the pre-intervention TGF-beta 1 values for each group (intragroup). Results: Comparing the differences in TGF-beta 1 levels between the L group (874.9 +/- 541.7 pg/mL) and the P group (-128.4 +/- 832.8 pg/mL) revealed that there was a statistically significant increase in TGF-beta 1 levels 30 days post-intervention in group L compared with the placebo group (p = 0.0379). Conclusions: This finding suggested that the significant increase in serum TGF-beta 1 levels in patients with CAT-induced hypothyroidism was associated with the thyroid LLLT procedure. Future studies of the effect of LLLT on TGF-beta 1 gene expression in thyroid tissue are necessary to confirm these findings.