Iodine deficiency 15–20 mg of iodine in the human body which is primarily concentrated in thyroid tissue and hormones, but 30% of iodine is distributed in other tissues, including mammary glands, eyes, gastric mucosa, choroid plexus, arterial walls, the cervix, and salivary glands. In the cells of these tissues, iodide enters directly by sodium-iodide symporter (NIS). The diagnostic workup of a suspected iodine deficiency includes signs and symptoms as well as possible risk factors mentioned above. A 24-hour urine iodine collection is a useful medical test, as approximately 90% of ingested iodine is excreted in the urine. For the standardized 24-hour test,
Isotopes of iodine and 1970s reached about 10). I differs from Cl in that its half-life is longer (15.7 vs. 0.301 million years), it is highly biophilic, and occurs in multiple ionic forms (commonly, I and IO), which have different chemical behaviors. This makes it fairly easy for I to enter the biosphere as it becomes incorporated into vegetation, soil, milk, animal tissue, etc. Of the many isotopes of iodine, only two are typically used in a medical setting: iodine-123 and iodine-131. Since I has both a beta and gamma decay mode, it can be used for radiotherapy or for imaging. I, which