Evaluation of low intensity laser effects on the thyroid gland of male mice.

OBJECTIVE The purpose of this study was to assess whether there were alterations in the thyroid hormone plasma levels under infrared laser irradiation, in the thyroid gland region. BACKGROUND DATA Studies have demonstrated that infrared laser can cause alterations in thyroid glands. METHODS Sixty-five albino male mice were used and assigned to five groups (n = 13), with differences in the times that they were sacrificed. Irradiation procedures consisted of an infrared diode laser emitting at 780 nm, at 4 J/cm(2) energy density, in contact mode, point manner. Blood was collected before irradiation (group 1), and then at 24 h (group 2), 48 h (group 3) and 72 h (group 4), and 1 week (group 5) after the third irradiation. The collected material was used for clinical analysis to evaluate the T(3) (triiodothyronine) and T(4) (thyroxin) hormones. Five animals were used for light microscopy analysis. RESULTS A statistically significant hormonal level alteration between the first day and 7 days after the last irradiation was found. CONCLUSIONS It was concluded that low-level laser therapy (LLLT) of the thyroid gland may affect the level of thyroidal hormones.