The mode of action of perchlorate ions on the iodine uptake of the thyroid gland

Abstract

In the course of investigating the physiological iodine uptake mechanism in the thyroid gland, it was found that perchlorate ions concentrate in the thyroid tissue and compete with iodide ions for the limited uptake capacity of the thyroid gland. Using KClO 4 labelled with Cl 36 and O 18, it was shown that ClO 4 − does not undergo metabolization in the human body and it is excreted at a fast rate; these results exclude the participation of ClO 4 − in a redox reaction. It was suggested that the competition of the perchlorate ion is due to its similarity in size to that of the iodide ion. Other ions of a size similar to ClO 4 −, including monofluorosulphonates, difluorophosphates and fluoroborates were shown to exhibit a similar action on the iodine uptake like perchlorate ions. These findings on the behaviour of perchlorate and related ions may be relevant to the elucidation of the iodide trapping mechanism of the thyroid gland.