Iodine induced hyperthyroidism

Blockers are usually used as adjunctive therapy with antithyroid drugs, RAI, or iodides when treating Graves disease or toxic nodules in preparation for surgery or in thyroid storm. /3-Blockers are primary therapy only for thyroiditis and iodine-induced hyperthyroidism. 

In older patients with goiter due to iodine deficiency there is a risk of provoking hyperthyroidism by increasing iodine intake (p. 247) During chronic maximal stimulation, thyroid follicles can become independent of TSH stimulation ( autonomic tissue"). If the iodine supply is increased, thyroid hormone production increases while TSH secretion decreases due to feedback inhibition. The activity of autonomic tissue, however, persists at a high level thyroxine is released in excess, resulting in iodine-induced hyperthyroidism. 

The perchlorate ion of potassium perchlorate, KCIO4, is a competitive inhibitor of thyroidal 1 transport via the Sodium Iodide Symporter (NIS).This drug can cause fatal aplastic anemia and gastric ulcers and is now rarely used. If administered with careful supervision, in limited low doses and for only brief periods, serious toxic effects can be avoided. The compound is especially effective in treating iodine-induced hyperthyroidism, which may occur, for example, in patients treated with the antiar-rhythmic compound amiodarone. Perchlorate ion can also be used in a diagnostic test of 1 incorporation into Tg, the so-called perchlorate discharge test. 

Iodine-induced hyperthyroidism People living in iodine-deficient areas people with a... 

The use of iodine has been held responsible for the increasing frequency of relapse of Graves disease in the USA. Treatment of more severe cases of iodine-induced hyperthyroidism can be difficult, as thyroid synthesis inhibitors are not immediately active and 131I cannot be used because of low thyroid uptake. The carefully supervised combination of perchlorate and methimazole is effective (40), but surgery has also occasionally been advocated. 

A summary of the occurrence and epidemiology of iodine-induced hyperthyroidism has been published (41), based on the authors experience in Tasmania, Zaire, Zimbabwe, and Brazil. Another review has more specifically examined the cardiac features of iodine-induced hyperthyroidism and has emphasized the importance of awareness, monitoring, and treatment of such hyperthyroidism in areas in which iodine supplementation has been recently introduced (42). 

Because of reports of severe hyperthyroidism after the introduction of iodized salt in two severely iodine-deficient African counties (Zimbabwe and the Democratic Republic of the Congo), a multicenter study has been conducted in seven countries in the region to evaluate whether the occurrence of iodine-induced hyperthyroidism after the introduction of iodized salt was a generalized phenomenon or corresponded to specific local circumstances in the two affected countries (46). Iodine deficiency had been successfully eliminated in all of the areas investigated and the prevalence of goiter had fallen markedly. However, it was clear that some areas were now exposed to iodine excess as a result of poor monitoring of the quality of iodized salt and of the iodine intake of the population. In these areas, iodine-induced hyperthyroidism occurred only when iodized salt had been recently introduced. 

Kohn LA. A look at iodine-induced hyperthyroidism Recognition. Bull NY Acad Med 1975 51(8) 959-66. 

Stanbury JB, Ermans AE, Bourdoux P, Todd C, Oken E, Tonglet R, Vidor G, Braverman LE, Medeiros-Neto G. Iodine-induced hyperthyroidism occurrence and epidemiology. Thyroid 1998 8(1) 83-100. 

Dunn JT, Semigran MJ, Delange F. The prevention and management of iodine-induced hyperthyroidism and its cardiac features. Thyroid 1998 8(1) 101—6. 

Delange F, de Benoist B, Alnwick D. Risks of iodine-induced hyperthyroidism after correction of iodine deficiency by iodized salt. Thyroid 1999 9(6) 545-56. 

Povidone-iodine-induced hyperthyroidism is rarer than hypothyroidism (SEDA-20, 226), but a history of longterm use of iodine-containing medications should be considered when investigating the cause of hyperthyroidism (15). 

Shilo, S. and Hirsch, J. 1986. Iodine-induced hyperthyroidism in a patient with a normal thyroid... 

Adults goiter with its complications, hypothyroidism, impaired mental functions, iodine-induced hyperthyroidism (Hetzel and Wellby 1997). 

Hyperthyroidism and toxicity Iodine-induced hyperthyroidism A mild increase in the incidence of hyperthyroidism worldwide has been described following iodized salt programs (Connolly et al. 1970, Stewart et al. 1971, Bauch 1985, Koutras etal. 1999, Joseph 1989, Meng etal. 1989, Lobbers etal. 1989, Pickardt 1989). Joseph et al. (1980) reported that iodine intakes of < 100 xg per day pose no risk for patients with autonomous tissue due to iodine deficiency critical amounts are between 100 and 200 jg I per day. The absence of iodine deficiency in the Japanese population accounts for the absence of iodine-induced thyrotoxicosis (Nagataki 1987). Hyperthyroidism is easily controlled with antithyroid drugs. 

It has been known that excessive iodine intake results in goiter, hypothyroidism, or hyperthyroidism in humans (Institute of Medicine, 2001). The biological basis for iodine-induced hyperthyroidism (IIH) appears most often to be mutational events in thyroid cells that lead to autonomy of function. When the mass of cells with such an event becomes sufficient, and the iodine supply is increased, the subject may become thyrotoxic. These changes may occur in localized foci within the gland or... 

Perchlorate is a competitive inhibitor of the sodium-iodide symporter (NIS) and has been used in pharmacological doses to treat hyperthyroidism, especially iodine-induced hyperthyroidism. Perchlorate appears to be ubiquitous in the environment, and has been detected in trace amounts in the urine in almost all subjects evaluated both in the United States and Europe. In prospective clinical studies and environmental studies, there is no convincing evidence that environmental perchlorate adversely affects thyroid function. 

The incidence of iodine-induced hyperthyroidism is dependent on the iodine dose and the prevalence of goiter and, in connection with this, the occurrence of autonomies. 

Excessive/rlsk of adverse health consequences such as Iodine-Induced hyperthyroidism, autoimmune thyroid disease... 

More than adequate/rlsk of Iodine-Induced hyperthyroidism within 5-10 years In susceptible groups... 

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