Structural and functional state of the thyroid gland in patients with precancerous conditions of the stomach

Background. The mechanisms of the functional interaction of the stomach and thyroid gland are based on the biological action of thyroid hormones. According to the European guidelines MAPS II, precancerous conditions of the stomach include atrophy and intestinal metaplasia of the gastric mucosa. The purpose of the work is to evaluate the structural and functional changes in the thyroid parenchyma in patients with precancerous conditions of the stomach. Materials and methods. The study was conducted in 44 patients with precancerous conditions of the stomach: 32 (72.7 %) women and 12 (27.3 %) men aged 33 to 76 years, on average (59.7 ± 1.7) years. Upper endoscopy was performed using the EVIS EXERA III system with an Olympus 190 gastroscope (Japan). According to the results of endoscopic examination, patients were divided into groups: group I — 11 people with atrophy of the gastric mucosa without intestinal metaplasia, group II — 13 individuals with atrophy of the gastric mucosa with intestinal metaplasia, limited by the antrum or body of the stomach, group III — 8 patients with diffuse intestinal metaplasia on the background of the gastric mucosa atrophy. The groups were representative by age and gender. All examined patients underwent a sonological examination of the thyroid gland with the ultrasound scanner Toshiba Xario (Japan) using a multi-frequency linear transducer with a frequency of 5–12 MHz. To assess the functional state of the thyroid gland, the levels of thyroglobulin and thyroid-stimulating hormone in the blood serum were determined by the enzyme immunoassay. Results. A significant increase in the frequency of diffuse and focal changes in the thyroid gland was found in patients with diffuse spread of intestinal metaplasia in the stomach (p < 0.05), which is confirmed by a correlation between the frequency of intestinal metaplasia of the body and antrum of the stomach with the presence of thyroid nodules (r = 0.44, p = 0.003; and r = 0.40, p = 0.006, respectively). At the same time, an increase in the frequency of focal hyperplasia of the gastric mucosa was associated with irregular contours of the thyroid gland (r = 0.41, p = 0.03) and an increase in the density of the thyroid capsule (r = 0.49, p = 0.04) that were the signs of a chronic inflammatory process. The spread of gastric intestinal metaplasia was accompanied by an increase in serum thyroglobulin by more than 3 times (p = 0.0134). Moreover, the level of thyroid-stimulating hormone significantly decreased as the precancerous changes in the gastric mucosa worsened (p = 0.0474), and the correlation between the level of this hormone and the presence of intestinal metaplasia in the stomach body (r = –0.46, p < 0.05) indicates the need for further study of the role of thyroid hormones in the development of precancerous conditions of the stomach. Conclusions. Patients with precancerous conditions of the stomach have a high frequency of structural changes in the thyroid parenchyma (81.8 %) of both diffuse (75.0 % of cases) and focal (43.2 %) nature. The spread of intestinal metaplasia in the gastric mucosa correlates with structural changes in the thyroid parenchyma, which is accompanied by a significant increase in thyroglobulin and a decrease in thyroid-stimulating hormone level in the blood serum. The frequency of structural changes in the thyroid gland increases with the development of precancerous changes in the stomach that is confirmed by a positive correlation between changes in the structure of the thyroid gland and the presence of xanthomas of the gastric mucosa, which are markers of precancerous conditions of the gastric mucosa (r = 0.52, p = 0.03).