Radiation thyroiditis

Radio-iodine, I, diffusely kills thyroid cells resulting in eventual and inevitable hypothyroidism which often makes substitution with thyroxine necessary. Administered as capsules it is an effective oral treatment for hyperthyroidism. Patient should not be pregnant or become pregnant in the month following treatment. Breast-feeding is contraindicated. Painful radiation thyroiditis may occur. 

Radiation thyroiditis is an infrequent complication resulting in swelling and localized pain over the thyroid gland which subsides spontaneously or with anti-inflammatory or corticosteroid therapy (SEDA-1, 314). 

In hyperthyroidism the beneficial effects of a single dose may be felt in one month, and patients should be reviewed at 6 weeks to monitor for onset of hypothyroidism. The maximal effect of radioiodine may take 3 months. P-adrenoceptor blockade and, in severe cases, an antithyroid drug (but see footnote 1) will be needed to render the patient comfortable whilst waiting this is more likely when radioiodine is used for treatment of patients with relapsing thyrotoxicosis. Very rarely radiation thyroiditis causes excessive release of hormone and thyroid storm. Repeated doses are sometimes needed. 

Radloiodlne Treatment Radioiodine therapy is particularly well-suited for the treatment of autonomously functioning thyroid tissue. Radioactive iodine, like the natural element, is taken up by the thyroid gland via an active process (the sodium iodide symporter) and accumulates within the thyroid gland. The therapeutic effect occurs as a result of tissue destruction (radiation thyroiditis) caused by short-reached (3 radiation detection is enabled due to emission of a small portion of irradiation. The radioactive material is selectively trapped by the more active autonomously functioning cells and, to a lesser extent, by normal thyrocytes, which depend on TSH stimulation to increase iodine uptake. 

The side-effects of 3T treatment are usually minor, and most of them are transient. The most common are nausea, neck tenderness/radiation thyroiditis, gastric pain, sialadenitis and transitional loss of taste. Sialadenitis can be limited by liberal hydration and by lemon juice/drops taken on day 2 after 33T treatment. Repeated treatments, however, can make dryness of the mouth a problem. 

Endocrine Patients with moderate- or high-risk differentiated thyroid cancer undergo postsurgical I therapy for remnant ablation. In a comparison of 68 patients who received I in a dose of 1110 MBq and 115 patients who were given a dose of 3700 MBq there were similar ablation success rates, with a reduction in the frequency and severity of radiation thyroiditis in those treated with lower doses [2E]. 

Cherk MH, Kalff V, Yap KS, Bailey M, Tophss D, Kelly MJ. Incidence of radiation thyroiditis and thyroid remnant ablation success rates following 1110 MBq (30 mCi) and 3700 MBq (100 mCi) post-surgical 1 ablation therapy for differentiated thyroid carcinoma. Clin Endocrinol (Oxf) 2008 69(6) 957-62. 

Cholesterol biosynthesis is affected by dietary and hormonal factors as well as by various external influences. Cholesterogenesis is enhanced by radiation, thyroid hormones, hypophysectomy, various metal ions and surface active agents. Biosynthesis is inhibited by fasting, thyroidectomy, vanadium salts, and by feeding of cholesterol or some of its steroid precursors. These influences were reviewed by Kritchevsky et al. (1960). In most cases cholesterol synthesis from acetate is more severely inhibited than is synthesis from mevalonate, suggesting that the inhibition occurs at an early step in cholesterol biosynthesis. The inhibition of cholesterol biosynthesis by cholesterol feeding was shown to possess the characteristics of a negative feedback control system (Bucher et al., 1959). 

To prevent radioactive iodides from lodging in the thyroid gland during exposure to excessive radiation, a potential appHcation of iodine acting as a thyroid-blocker has arisen. Eor this purpose potassium iodide was recommended (66). 

Half-lives span a very wide range (Table 17.5). Consider strontium-90, for which the half-life is 28 a. This nuclide is present in nuclear fallout, the fine dust that settles from clouds of airborne particles after the explosion of a nuclear bomb, and may also be present in the accidental release of radioactive materials into the air. Because it is chemically very similar to calcium, strontium may accompany that element through the environment and become incorporated into bones once there, it continues to emit radiation for many years. About 10 half-lives (for strontium-90, 280 a) must pass before the activity of a sample has fallen to 1/1000 of its initial value. Iodine-131, which was released in the accidental fire at the Chernobyl nuclear power plant, has a half-life of only 8.05 d, but it accumulates in the thyroid gland. Several cases of thyroid cancer have been linked to iodine-131 exposure from the accident. Plutonium-239 has a half-life of 24 ka (24000 years). Consequently, very long term storage facilities are required for plutonium waste, and land contaminated with plutonium cannot be inhabited again for thousands of years without expensive remediation efforts. 

The nuclear explosions that devastated Hiroshima and Nagasaki killed 100,000 to 200,000 people instantaneously. Probably an equal number died later, victims of the radiation released in those explosions. Millions of people were exposed to the radioactivity released by the accident at the Chernobyl nuclear power plant. The full health effects of that accident may never be known, but 31 people died of radiation sickness within a few weeks of the accident, and more than 2000 people have developed thyroid cancer through exposure to radioactive iodine released in the accident. Even low levels of radiation can cause health problems. For this reason, workers in facilities that use radioisotopes monitor their exposure to radiation continually, and they must be rotated to other duties if their total exposure exceeds prescribed levels. 

Riches AC, Herceg Z, Bryant PE, et al. 1997. Radiation-induced transformation of SV40-immortalized human thyroid epithelial cells by single exposure to plutonium -particles in vitro. Int J Radiat Biol 72(5) 515-521. 

Stevens W, Stover BJ, Bruenger FW, et al. 1969. Some observations on the deposition of americium-241 in the thyroid gland of the beagle. Radiat Res 39 201-206. 

Cancer is the major latent harmful effect produced by ionizing radiation and the one that most people exposed to radiation are concerned about. The ability of alpha, beta, and gamma radiation to produce cancer in virtually every tissue and organ in laboratory animals has been well-demonstrated. The development of cancer is not an immediate effect. In humans, radiation-induced leukemia has the shortest latent period at 2 years, while other radiation induced cancers have latent periods >20 years. The mechanism by which cancer is induced in living cells is complex and is a topic of intense study. Exposure to ionizing radiation can produce cancer at any site within the body however, some sites appear to be more common than others, such as the breast, lung, stomach, and thyroid. 

Radiation is carcinogenic. The frequency of death from cancer of the thyroid, breast, lung, esophagus, stomach, and bladder was higher in Japanese survivors of the atomic bomb than in nonexposed individuals, and carcinogenesis seems to be the primary latent effect of ionizing radiation. The minimal latent period of most cancers was <15 years and depended on an individual s age at exposure and site of cancer. The relation of radiation-induced cancers to low doses and the shape of the dose-response curve (linear or nonlinear), the existence of a threshold, and the influence of dose rate and exposure period have to be determined (Hobbs and McClellan 1986). 

Gorbman, A. and M.S. James. 1963. An exploratory study of radiation damage in the thyroids of coral reef fishes from the Eniwetok Atoll. Pages 385-399 in V. Schultz and A.W. Klement, Jr. (eds.). Radioecology. Reinhold, New York. 

After the nuclear explosion at Chernobyl in 1986, Anatoly and other professors and physicians created a foundation, For the Children of Chernobyl. Their goal was to send children abroad for the summers for a reprieve from radiation exposure which impairs their immune systems and has resulted in unprecedented levels of thyroid cancer in children and adults. The first host country to respond to their call for help was India. Before long, the foundation was sending 30,000 children every summer to host families and programs in many countries, including Germany, England, Japan, the U.S., Spain, Italy and France. 

Long-term health effects from exposure to low-to-moderate doses of radiation include cancer of the thyroid, prostate, kidney, liver, salivary glands, and lungs Hodgkin s disease leukemia and increased numbers of stillbirths and genetic defects. Concerns about potential long-term health effects often lead to anxiety and depression problems among those exposed to radiation. 

Potassium iodine tablets can be used to reduce radioactive iodine exposure to the thyroid gland. According to the National Council of Radiation Protection and Measurement (NCRP), taking 130 milligrams of potassium iodine at or before exposure to radioactive iodine effectively blocks nearly 100% of radioactive iodine from reaching the thyroid.1 Waiting 4 hours after exposure to take potassium iodine... 

---