In excess iodine exposure, an acute increase in intracellular iodine concentration in normal glands interferes with iodination and temporarily inhibits thyroid hormone synthesis and release. The gland subsequently escapes from this effect perhaps by a reduction in the affinity of the iodide trap. Use has been made of this effect in preparing thyrotoxic patients for surgery by administration of iodide solution for several days prior to operation. This treatment blocks formation of hormone and also inhibits release of hormone from the thyroid gland.
