What does the thyroid gland and the tragedy is Japan have in common? Quite a lot actually. First, the thyroid gland is one of the largest endocrine glands in the body. It is found in the neck, below the thyroid cartilage (also known as the Adam’s Apple) and at approximately the same level as the cricoid cartilage. The thyroid controls how quickly the body uses energy, makes proteins, and controls how sensitive the body should be to other hormones.
The thyroid gland participates in these processes by producing thyroid hormones, the principal ones being triiodothyronine (T3) and thyroxine (T4). These hormones regulate the rate of metabolism and affect the growth and rate of function of many other systems in the body. T3 and T4 are synthesized utilizing both iodine and tyrosine. The thyroid gland also produces calcitonin, which plays a role in calcium homeostasis.
The thyroid gland is controlled by thyroid-stimulating hormone (TSH) produced by the pituitary (to be specific, the anterior pituitary) and thyrotropin-releasing hormone (TRH) produced by the hypothalamus. The thyroid gland gets its name from the Greek word for “shield”, after the shape of the related thyroid cartilage. The most common problems of the thyroid gland consist of an overactive thyroid gland, referred to as hyperthyroidism, and an underactive thyroid gland, referred to as hypothyroidism.
So, what does this have to do with an earthquake off the cost of Japan? The chance of radioactive materials being released into the atmosphere. Radioactive fallout exposure can come from inhalation and intake from contaminated water and food. When radioactive materials are taken into the body, they can be deposited in bones, glands and other tissues where they cause ongoing damage.
One of the first concerns is protecting the thyroid gland from radioactive iodine, I-131, which is created in a nuclear explosion. Radioactive Iodine, I-131, is absorbed from the air, water and from food that is exposed to the fallout. The radioactive iodine, I-131, is deposited in the thyroid gland where the radiation that it emits damages the thyroid causing hypothyroidism and often cancer.
The defense against this problem is to take large doses of iodine orally to saturate the thyroid gland with healthy iodine so there is no room to store the radioactive iodine from the environment. The usual form of iodine supplementation used for this purpose is either potassium iodide, KI, or potassium iodate, KIO3. Potassium Iodate, KIO3, is the preferred form because it is less bitter and is better tolerated, especially by children.
If there were a nuclear meltdown in Japan, radioactive iodine would be released which can damage your thyroid gland or even cause thyroid cancer. Taking a high dose of iodine to act as a thyroid blocker is the only known protection for this problem. The iodine should be taken immediately before exposure to the fallout, but immediately after exposure would also be beneficial. Additional doses taken daily during the exposure period would be necessary for effective protection.