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 Lugol's iodine, by contrast, has no alcohol, and has twice the mass of potassium iodide as of elemental iodine. Alcohol content in the tincture of iodine can be determined by the methods of Alcock, Roscoe - Schorlemmer and Thurston - Thurston. As both USP solutions contain elemental iodine, which is moderately toxic when ingested in amounts larger than those required to disinfect water, tincture of iodine is sold labelled “for external use only,” and used primarily as a disinfectant. Tincture of iodine is often found in emergency survival kits, used both to disinfect wounds and to sanitize surface water for