Goiter high iodine intake

Iodine intake level (based on UI) affects the type of benign thyroid disease (Laurberg et ai, 2001). A number of studies (Laurberg et ai, 2001 Suzuki et al., 1975 Stanbury et ai, 1998) indicated the following specific associations a high iodine intake causes endemic goiter (Suzuki etai, 1975). Aswitch from low to sufficient iodine... 

Over the years, people living with iodine deficiency tend to develop multifocal thyroid autonomy, and multinodular toxic goiter is a common cause of hyperthyroidism. The difference in relative distribution of the four most common causes of hyperthyroidism in Iceland, with high iodine intake, and Judand, Denmark, with mild-to-moderate iodine deficiency, is shown in Figure 47.3. In Iceland, Graves ... 

Figure 47.3 Nosological types of hyperthyroidism with different iodine intake levels. Relative frequency of the four most common nosological types of hyperthyroidism in Iceland, with relatively high iodine intake from consumption of fish and high iodine content of dairy products, and from East Jutland, Denmark, with mild-to-moderate iodine deficiency. MNTG, multinodular toxic goiter GD, Graves disease STA, solitary toxic thyroid adenoma SAT, subacute thyroiditis. Data from Laurberg et al., (1991).

The assessment of iodine intake and status is important in elderly subjects. Mild-to-moderate iodine deficiency is associated with a high incidence and prevalence of goiter and nodular hyperthyroidism in middle-aged and elderly subjects (Laurberg et ai, 1991 Pedersen et ai, 2002). In populations with high iodine intake, there is an increased risk of hypothyroidism, especially among... 

Except Formosa, all the other cities had a high iodine intake. In the case of Paso de la Patria, which was the only city without endemic goiter, the urinary iodine content... 

In Litoral North, most of the children have endemic goiter with high iodine intake, the major reason being the huge consumption of cassava in their diet. 

In the NOA part of Argentina, iodine deficiency is due to the consumption of insufficiently or noniodized local brands of salt. In some other places with a very high iodine intake, the presence of environmental goitrogens is responsible for the high prevalence of goiter. 

It is difficult to define the normal range of iodine intake in humans, and despite efforts to provide iodine supplementation in many geographic areas of the world, endemic iodine deficiency and attendant goiter remain a world health problem (147). Exposure to excess iodine may sometimes lead to the development of thyroid disease. This unusual type of iodide-induced goiter has been found, for example, in 10% of the population of a Japanese island where fishermen and their families consume large quantities of an iodine-rich seaweed and have an iodine intake as high as 200 mg/d (148). 

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. 

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