Thyroid gland cancer

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. 

Th Toid cancers are often treated with radioactive iodine because the thyroid gland preferentially absorbs iodine. 

A low RAIU indicates the excess thyroid hormone is not a consequence of thyroid gland hyperfunction. This may be seen in painful subacute thyroiditis, painless thyroiditis, struma ovarii, follicular cancer, and factitious ingestion of exogenous thyroid hormone. 

In group I, the use of animal cancer data obtained in the fiver, kidney, forestomach, and thyroid gland are perceived by some as being hyperresponsive, too sensitive, and of limited value and utility in the animal cancer data obtained in group I organs. The liver is such a responsive and important organ in the interpretation of cancinogenesis data that the discussion of this subject area has been broken up into three chapters for human, rat, and mouse data. Peroxisome proliferation in the liver, particularly in mice, is an area of interpretive battle, as in many cases the metabolism and mechanisms involved are not relevant to man. 

Iodine is an essential nutrient element required for thyroid gland. It is added to salt and to animal feeds for the prevention of goiter. In medicine it is used as a therapeutic reagent for the treatment of various thyroid-related diseases. It also is used as an antiseptic. Radioactive isotopes of iodine are used for treating thyroid cancer, heart diseases including tachycardia, and as a tracer for diagnosing certain diseases. 

TSH is approved for medical use as a diagnostic aid in the detection of thyroid cancer/thyroid remnants in post-thyroidectomy patients. Thyroid cancer is relatively rare, exhibiting the highest incidence in adults, particularly females. First-line treatment is surgical removal of all or most of the thyroid gland (thyroidectomy). This is followed by thyroid hormone suppression therapy, which entails administration of T3 or T4 at levels sufficient to maintain low seum TSH levels through the negative feedback mechanism mentioned earlier. TSH suppression is required... 

Holm, L.E., Eklund, G., and Limdell, G. (1980a). Incidence of malignant thyroid tumors in humans after exposure to diagnostic doses of iodine-131 II. Estimation of thyroid gland size, thyroid radiation dose, and predicted versus observed number of malignant thyroid tumors, J. Natl. Cancer Inst. 65,1221. 

Therapeutic Techniques. Probably the most prominent therapeutic use of radiopharmaceuticals is radioactive iodine in the treatment of metastatic thyroid cancer. 131I has a half-life of about 8 days and emits gamma and beta rays. When iodine salts are taken into the body, most of the dose is concentrated in the thyroid gland. A dose of radioactive iodine salt similarly concentrates in the thyroid gland. When there is a cancer in the thyroid gland, or the gland is overactive (hyperthyroidism), the excessive... 

Medical x-rays provided one of the first applications of radioisotopes. In 1914, the wounded from World War 1 were pouring into Paris hospitals. Marie Curie converted a Renault car into the first mobile radiological unit and drove it from hospital to hospital. Radioisotopes are now widely used in medicine to diagnose, study, and treat illness. A physician can determine, for example, how and at what rate the thyroid gland takes up iodine by using iodine-131 as a radioactive tracer and cobalt-60 is used to kill rapidly growing cancer cells. 

Whatever the mechanism may be, the high incidence of associated papillary thyroid cancer mandates at a minimum that one ask about the use of minocycline in any patient who has an enlarged thyroid. The authors recommended that if a patient has taken minocycline in the past, biopsy and possibly removal of the thyroid gland is advisable. 

Birkedal C, Tapscott WJ, Giadrosich K, Spence RK, Sperling D. Minocycline-induced black thyroid gland medical curiosity or a marker for papillary cancer Curr Surg 2001 58 471-1. 

The anthropogenic radionuclides of most concern are those produced as fission products from nuclear weapons and nuclear reactors. The most devastating release from the latter source to date resulted from the April 26, 1986, explosion, partial meltdown of the reactor core, and breach of confinement structures by a power reactor at Chernobyl in the Ukraine. This disaster released 5 x 107 Ci of radionuclides from the site, which contaminated large areas of Soviet Ukraine and Byelorussia, as well as areas of Scandinavia, Italy, France, Poland, Turkey, and Greece. Radioactive fission products that are the same or similar to elements involved in life processes can be particularly hazardous. One of these is radioactive iodine, which tends to accumulate in the thyroid gland, which may develop cancer or otherwise be damaged as a result. Radioactive cesium exists as the Cs+ ion and is similar to sodium and potassium in its physiological behavior. Radioactive strontium forms the Sr2+ ion and substitutes for Ca2+, especially in bone. 

The neutral isotope of iodine is an essential element in the human body most of the iodine-127 is located in the thyroid gland. Iodine s radioactive isotope, iodine-131, is readily absorbed in the body, where it becomes concentrated in the thyroid gland and may produce cancers. Exposure to radioactive iodine is an increasing concern since it is produced by fission reactions in nuclear reactors and by nuclear weapons tests. 

Adjunctive diagnostic used in screening of cancer patients with thyroid cancer without thyroid glands... 

Calcitonin is a peptide hormone produced by the C cells of the thyroid gland (in mammals). It acts on bone (inhibiting osteoclasis) to reduce the rate of bone turnover, and on the kidney to reduce reabsorption of calcium and phosphorus. It is obtained from natural sources (pork, salmon, eel), or S3mthesised. The t/ varies according to source t/ human is 10 min. Antibodies develop particularly to pork calcitonin and neutralise its effect synthetic salmon calcitonin (salcatonin) is therefore preferred for prolonged use loss of effect may also be due to down-regulation of receptors. Calcitonin is used (s.c., i.m. or intranasally) to control hypercalcaemia (rapid effect), Paget s disease of bone (relief of pain, and to relieve compression of nerves, e.g. auditory cranial), metastatic bone cancer pain, and postmenopausal osteoporosis. 

The radiation given off by iodine-131 in the form of beta particles is used to treat cancer of the thyroid gland. Write the nuclear equation to describe the decay of an iodine-131 nucleus. 

Workers chronically exposed to thiram and concurrently ingesting alcohol have developed skin reactions without any systemic effects. In these cases, the skin becomes red, flushed, and itchy. In susceptible individuals, thiram can cause dermatitis even without concomitant alcohol ingestion, and sensitization of the skin has occurred on the hands, forearms, and feet of exposed individuals. The International Agency for Research on Cancer notes that studies from the USSR report thyroid gland enlargement, one case of thyroid cancer, and seven cases of thyroid abnormalities in a group of 105 workers exposed to thiram at unspecified concentrations for more than 3 years. 

This isotope of iodine is also used in the treatment of thyroid cancer. Because of its preferential absorption in the thyroid gland, it dehvers radiation where it is needed. 

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