The JTA guidelines for the diagnosis and management of thyroid nodules are now under preparation

RADIATION RISKS TO HEALTH：A Joint Statement from the American Association of Clinica Endocrinologists, the American Thyroid Association, The Endocrine Society and the Society of Nuclear Medicine

Iodine and Japan Nuclear Accident

The JTA guidelines for the diagnosis and management of thyroid nodules are now under preparation

A committee was organized to develop the JTA guidelines for the diagnosis and management of thyroid nodules. The committee consists of 29 members including physicians, surgeons, pathologist, radiologists and specialists in laboratory medicine and is headed by Dr. Hirotoshi Nakamura (Chairperson, Hamamatsu University School of Medicine). The first meeting was held in November 2008, and since then the meeting has been held regularly. Since the guidelines from the Japan Association of Endocrine Surgeons describe in detail about papillary carcinoma, the discussion is mainly focused on the clinical problems in the diagnosis and management of follicular carcinoma,

The following important clinical subjects are under consideration：

1．

Classification and prevalence of thyroid nodules．

2．

Flow chart of diagnostic procedures．

3．

Recommendations for diagnosis of thyroid nodules．

4．

Recommendations for management of thyroid nodules．

5．

Clinical data in Japanese population．

6．

Comparison with the guidelines in foreign countries．

Iodine and Japan Nuclear Accident

International Council for the Control of Iodine Deficiency Disorders Statement for Publication March 19, 2011

On March 11th Japan experienced a devastating earthquake followed by a tsunami resulting in catastrophic damage and loss of life. This natural disaster in turn caused a manmade disaster by severely damaging four nuclear reactors with the ongoing release of radioactivity. Of particular concern is iodine (I)-131, the unstable, radioactive isotope of iodine. Normally, stable iodine is an essential element for the thyroid gland to produce thyroid hormone that is required for the optimal development of the human brain. As a result, brain damage from iodine deficiency in the fetus and developing child is the leading cause of preventable mental retardation.

The requirement for iodine in adults and children is about 150 micrograms a day, usually in the form of iodized salt. Pregnant and breastfeeding women require more iodine; the minimum amount for them being 250 micrograms a day. My organization, ICCIDD, along with UNICEF, WHO and other agencies have been strong advocates of the use of iodized salt. Significant iodine deficiency occurs in about 2 billion people or one- third of the global population. As an example of the importance of this micronutrient, administration of iodine to population living in areas of moderate to severe iodine deficiency results in an average increase of 10 to 13 points in their IQ.

When a nuclear reactor malfunctions, enormous amounts of the radioactive isotope of iodine (I-131) is released into the atmosphere and will be deposited on crops and pastures and can then enter the food chain mainly, but not exclusively, through milk. When taken up by the human thyroid, the I-131 itself produces radiation that damages the gland and strongly increases the risk of developing thyroid cancer. The risk for thyroid cancer is greatest in children. The administration of a large stable iodine dose of 130 milligrams (mg) which is one thousand times the normal intake dilutes the I-131 and limits accumulation of the radioactive isotope in the thyroid. Iodine in the form of potassium iodide (KI) administered within 1-2 hours after internal contamination with I-131 can block more than 90% of the thyroid uptake. Taking KI more than 4 hours after the event provides little protection. In an iodine-sufficient population, the acute administration of iodized salt has little or no beneficial effect. However the presence of iodine deficiency increases the amount of radioactivity taken up by the thyroid. ICCIDD recommends adherence to the recommendations provided by the U.S. Center for Disease Control and Prevention (CDC) http://emergency.cdc.gov/radiation/japan/ki.asp.
Fortunately, the Japanese population has a high intake of iodine, even without using iodized salt, due to a diet containing iodine-rich substances like seaweed.

ICCIDD recommends the importance of maintaining a normal iodine intake for all humans that will lessen the uptake of the I-131 radioisotope after a nuclear accident. Ingestion of excessively large amounts of iodine in the absence of exposure to I-131 is not helpful and can cause side effects such as underactivity (hypothyroidism) or overactivity (hyperthyroidism) in people with underlying thyroid disease.