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,
Tincture of iodine drinking. When an alcohol solution is not desirable for this purpose, the alcohol-free Lugol's iodine, an aqueous solution of iodine in potassium iodide solution, or else povidone-iodine (brand names Wokadine, Betadine), a PVPI solution, can be used. Small amounts may be added to suspect drinking water as a disinfectant (typically 5 mg free iodine per liter, or 5 drops of 2% tincture). Though this treatment is effective against bacteria and virus, it does not protect against protozoan parasites such as "Cryptosporidium" and "Giardia". Iodine solution is used to sanitize the surface of fruit and vegetables for bacteria and virus. The