Background. Violation of the principles of direct and negative feedback regulation of endocrine functions leads to nodular goiter. The structure and quantitative changes of thyroid gland can be assessed more informatively and accurately by polarization biomedical optics. The purpose was to substantiate the possibility of using polarization biomedical optic methods in the diagnosis of nodular thyroid goiter based on the application of an integrative pathophysiological approach of the principle of direct and negative feedback regulation of endocrine functions. Materials and methods. Two groups of patients were studied: control group 1 — healthy donors (n = 51), study group 2 — patients with nodular goiter (n = 51), who underwent a thyroid fine needle biopsy for diagnostic purposes. The fundamental idea of polarization biomedical optics is based on two analytical approaches: statistical and topographic (fractal). Instrumental laser methods were used such as polarization, interference, digital holographic, as well as computer and analytical methods: statistical and multifractal. The statistical parameters of polarization azimuth maps, polarization azimuth of phase and multifractal spectra of digital microscopic images of native histological sections of thyroid biopsy in patients with nodular goiter were determined quantitatively with calculation of the mean, dispersion, asymmetry and kurtosis. The significance of differences compared to the controls taken as 100 % was evaluated using the Student’s parametric test (p < 0.05). Results. There was a significant increase in the asymmetry and kurtosis of the polarization azimuth, a significant inhibition of the mean of polarization azimuth of phase digital microscopic images of native histological sections of thyroid biopsy in patients with nodular goiter, a significant increase in the asymmetry and kurtosis of digital microscopic images of native histological sections of thyroid biopsy in patients with nodular goiter. A significant increase in dispersion and a probable decrease in the asymmetry and kurtosis of multifractal spectra of polarization azimuth maps of digital microscopic images of native histological sections of thyroid biopsy in patients with nodular goiter were shown. Conclusions. There was a significant increase in the biophysical optical parameters of digital microscopic images of native histological sections of thyroid biopsy in patients with nodular goiter due to an increase in colloidal follicles and the growth of connective tissue around them. A probable inhibition of the average azimuth of polarization of phase digital microscopic images of native histological sections and a significant decrease in the asymmetry and kurtosis of multifractal spectra of polarization azimuth maps of digital microscopic images of native histological sections of thyroid biopsy in patients with nodular goiter are caused by the activation of thyrocytes as an amorphous component as a result of activation of the dysregulatory pathological process due to violations of the principle of direct and negative feedback regulation of endocrine functions.
