Damage of Endocrine System

Abstract

Fluoride is abundance in nature and can spread to the human body through the water, air, or food. Long-term intake of excessive amount of fluoride may damage skeleton and teeth, and also soft tissues, such as the endocrinological system. Here, we briefly focus on the influence of fluoride on thyroid gland, parathyroid gland, insulin sensitivity, and gonads, as well as the possible mechanism of fluoride toxicity. A large number of studies have shown that children in endemic fluorosis areas have significant thyroid dysfunction and changes in intelligence compared with children in normal areas, which may be influenced by minerals associated with inhibiting the expression of sodium iodide symporter and the activities of Na+-K+-ATPase. The majority of studies confirm that high accumulation of fluoride reduces the level of free calcium in the body and increases parathyroid hormone (PTH) and PTH-related peptide. In turn, more PTH may lead to abnormal calcium homeostasis and bone metabolism. Moreover, a correlation was observed between long-term exposure with fluoride and the increased secretion of insulin resistance, which may cause the changes in bone metabolism. Probably, fluoride may exert a negative effect on the level of sex hormone and impair hypothalamic-pituitary-testicular axis and hypothalamic-pituitary-ovarian axis, which may be resulted from the abnormal occurrences of genes, miRNA and estrogen receptor and gene polymorphism.