The impact of hyperthyroidism on parathyroid hormone content in malignant growth

Hyperthyroidism is caused by increased synthesis and secretion of thyroid hormones. It increases the risk of some malignant neoplasms. The thyroid gland and parathyroid glands have a common embryological origin. Parathyroid hormone (PTH) is secreted by the cells of the parathyroid glands. The aim of the study was to determine the level of parathyroid hormone in the blood serum, tumor, skin and thyroid/parathyroid gland complex in C57BL/6 mice of both sexes with Lewis lung carcinoma and induced hyperthyroidism. Materials and Methods. C57BL/6 mice of both sexes (n=112) were used in the trial. The animals were divided into experimental groups: intact group (n=16); control group (n=32) – mice with induced hyperthyroidism; comparison group (n=32) – mice with subcutaneous inoculation of Lewis lung carcinoma (LLC); main group (n=32) – mice with subcutaneous inoculation of LLC and induced hyperthyroidism. The PTH content in blood serum, skin, tumor and organ complex “thyroid gland/parathyroid glands” was determined using ELISA kits (XEMA, Russia). Results. The LLC growth in animals with hyperthyroidism was accompanied by PTH increase in the blood serum of animals of both sexes: in females it was 1.5 times higher compared to that in the intact group and the group with isolated LLC, and 1.4 times higher compared to that in the group of animals with hyperthyroidism only, in males it was 2.6 and 1.6 times higher compared to that in the intact group and the group with hyperthyroidism respectively. In the skin of females of the main group, the PTH level exceeded the intact values by 9 times, in males – by 2.8 times. In the skin of animals with a combined pathology (LLC and hyperthyroidism), PTH concentration in females was 6 times higher, and in males 4 times higher compared to mice with isolated LLC. The combination of LLC and hyperthyroidism also affected the organ complex “thyroid gland/parathyroid glands”: PTH level exceeded intact values by 1.7 times in females, by 3.6 times in males, and the corresponding values in the group of mice with LLC by 1.5 and 5.8 times, respectively.