Isotopes of iodine and non-radioactive materials can be described as "cold." There are instances in which cold iodide is administered to people in order to prevent the uptake of hot iodide by the thyroid gland. For example, blockade of thyroid iodine uptake with potassium iodide is used in nuclear medicine scintigraphy and therapy with some radioiodinated compounds that are not targeted to the thyroid, such as iobenguane (MIBG), which used to image or treat neural tissue tumors, or iodinated fibrinogen, which is used in fibrinogen scans to investigate clotting. These compounds contain iodine, but not in the iodide form. However, since they may
Tincture of iodine Strong Iodine Tincture is defined in the NF as containing in each 100 mL, 6.8 to 7.5 gram of iodine, and 4.7 to 5.5 gram of potassium iodide. Purified water is 50 mL and the balance is alcohol. This 7% tincture solution is about 3.5 times more concentrated than USP 2% tincture. As in the case of Lugol's iodine, the role of iodide in the solution is to increase the solubility of the elemental iodine, by turning it to the soluble triiodide anion I. However, since iodine has moderate solubility in ethanol, it is also assisted by this solvent directly.