# Iodine --- **Iodine** is an essential [[mineral]]. It is necessary for producing [[thyroid hormone]]. ## Iodine in the Lab In the [[labs]] we can use iodine to test for [[starch]] with **IKI**, or **iodine-potassium iodide**. When IKI is dropped in water, it turns a yellow color, but in the presence of starch it turns blue. This can be used in an experiment such as one testing if [[amylase]] breaks down [[starch]] in solution, and if so, how fast. ## Iodine in Biology & Medicine Iodine a necessary mineral for us to consume because it is essential for making [[thyroid hormone]]. I$_{131}$ is a radioactive iodine isotope that can be used to eradicate the [[thyroid]]. Since the thyroid is the only place in the body that really uses iodine, it will suck up the radioactive iodine and fry itself. This is used sometimes to treat [[hyperthyroidism]] or [[thyroid cancer]]. ___