TPO and hypothyroidism: With such considerations, the objective of this research was to assess the safety and effects of LLLT 6 years after completion of RCT [6] by investigating thyroid nodules, the LT4 dose required to treat hypothyroidism, the concentrations of anti-TPO and anti-thyroglobulin antibodies (anti-Tg), and the color Doppler ultrasound (CDU) images.