Cretinism Iodine deficiency

A number of dietary deficiencies may increase the risk of deleterious cyanide effects. Iodine deficiency is involved in the etiology of such thyroid disorders as goiter and cretinism. These disorders may be exacerbated by excess exposure to cyanide (Delange and Ermans 1971 Ermans et al. 1972). Protein deficiencies and vitamin B12, riboflavin and other vitamins and elemental deficiencies may subject people... 

A deficiency of iodine results iu insufficient synthesis of thyroxine and a low plasma level, so that secretion of TSH is increased in an attempt to stimulate synthesis but this results in enlargement of the thyroid gland (goitre). Iodine deficiency in pregnancy impairs brain development in the foetus, causing mental retardation (known as cretinism). Indeed iodine deficiency is one of the major public health issues worldwide an estimated 200 million people are affected. 

The therapeutic strategy should rely on preventative measures. Endemic goitre and endemic cretinism as well as more subtle deficits of neurological function associated with iodine deficiency have been shown to be prevented with adequate iodine prophylaxis. Adequate and continuous supply is the key to successful prevention programmes. 

Congenital (cretinism) Athyreosis or ectopic thyroid, iodine deficiency TSH receptor-blocking antibodies Absent or present Severe... 

Nonmetallic elements predominating in the ash are phosphorus (700 g in the human body), sulfur (175 g), and chlorine (105 g). Not only are these three elements essential to all living cells but also selenium, fluorine, silicon (Box 4-B), iodine, and boron are needed by higher animals and boron by plants (Fig. 1-17). Iodine deficiency may affect one billion human beings and may cause 20 million cases per year of cretinism, or less severe brain damage.158... 

Iodine must be present in the normal diet to prevent iodine-deficiency goiter or cretinism, and iodine deficiency-related disorders are still a worldwide (although preventable) group of diseases that affect about 150 million people in at least 40 countries. The WHO sponsored a program to control these disorders by the year 2000 (1,2), and since 1990 there has been a remarkable progress in prevention of iodine deficiency disorders. However, by the year 2000 one-third of the population affected by iodine deficiency disorders still did not have access to iodized salt (3). 

Or, to put it more positively, by adding small amounts of iodide to common salt we can prevent the medical condition known technically as cretinism, a life-long affliction of innately low intelligence caused by iodine deficiency, and which causes permanent brain damage. Nor does this simple dietary requirement cost very much. To provide all 6.5 billion people on the planet with the 70 micrograms of iodine they need every day would require only 166 tonnes of iodine per year, which represent a mere 2% of the iodine the world produces annually. This is an amount that chemists could easily extract from seaweed, making it a sustainable resource, and indeed this was once the way they obtained this remarkable element. 

Another example of a maternal condition that contributes to birth defects is low circulating iodine. Cretinism is one of the most profound, but completely preventable, syndromes of malformation known. Characteristic consequences of prenatal iodine deficiency include pervasive mental and physical retardation, deaf-mutism (due to primary malformation of the inner ear), lack of muscle tone with a spastic or rigid walk, and failure to attain a height at maturity of more than 1 m. Today, this condition (known as endemic cretinism) is most prevalent in impoverished areas of African and East Asian countries. Prior to implementation of a national program of iodized salt in the early part of the twentieth century, endemic cretinism was commonplace in Switzerland. After institution of iodized salt, deaf-mutism declined 50% within 8 years and no cretins have been born in that country since 1930. 

Hypothyroidism (thyroid hormone deficiency) may result from autoimmune disease (Hashimoto s disease) or from deficient synthesis of TSH or TRH (thyroid-stimulating hormone-releasing factor). Because adequate ingestion of iodine is a prerequisite for thyroid hormone synthesis, iodine deficiency also causes hypothyroidism. In children, thyroid hormone deficiency (called cretinism) causes depressed growth and mental retardation. Severe hypothyroidism in adults (myxedema) results in symptoms such as edema (abnormal fluid accumulation) and goiter. Hypothyroidism is usually treated with hormone replacement therapy. 

A second example of an application of the controlled-release technology developed by Rhone-Poulenc is the Rhodifuse lode system (ref. 6). This system is commercialized by Rhone-Poulenc RORER for the treatment of iodine deficiency. Lack of iodine in the diet can cause serious disorders such as goiter and cretinism in adults, growth disorders in children, and fetal death in pregnant women. This... 

Iodine in minute quantity is a normal constituent of the human body and the average person requires a daily dose of 0 000,017 gm. Absence of the requisite amount leads to general debility and in more severe cases to goitre or big-neck . In very severe cases mental weakness develops known as cretinism, from Latin creta, chalk, because of its prevalence in Alpine districts. In Switzerland sodium iodide is added to table salt by legal regulation to ensure that everybody receives his necessary ration of iodine. In Britain there are several areas of iodine deficiency in the soil and addition of iodides to the feeding-stuffs of cattle, etc, effects an enormous improvement in the herds. 

Iodine deficiency causes goiter in animals (and cretinism in humans) (Meng 1992, Anke et al. 2000). Iodine is a component of the important thyroid hormones, and... 

RELATION OF IODINE TO THYROID FUNCTION Normal thyroid function requires an adequate intake of iodine without this, thyroid hormone cannot be made, TSH is secreted in excess, and the thyroid becomes hyperplastic and hypertrophic. The enlarged and stimulated thyroid becomes remarkably efficient at extracting the residual traces of iodide from the blood, developing an iodide gradient that may be 10 times normal. In mild-to-moderate iodine deficiency, the thyroid usually succeeds in producing sufficient hormone, in part by preferentially secreting T. In more severe deficiency, as is common in some parts of the world, adult hypothyroidism or cretinism may occur. 

Perhaps the most striking illustration of the pervasive developmental effects of thyroid hormones is provided by children with severe thyroid hormone deficiency from early childhood, a condition termed cretinism. This may either be endemic in regions of severe iodine deficiency or sporadic due to failure of the thyroid to develop normally or defects in the synthesis of thyroid hormone. Affected children are dwarfed with short extremities, have mental retardation, and are inactive and listless. Other manifestations include facial puffiness, enlarged tongue, dry and doughy skin, slow heart rate, and decreased body temperature. Eor full recovery, treatment of patients with cretinism must be initiated before these florid features are apparent. Thus, pregnant women in areas of endemic cretinism due to iodine deficiency are supplemented with iodine and aU newborns are screened for thyroid hormone deficiency in many developed nations. 

Thyroid Hypofunction Hypothyroidism is the most common disorder of thyroid function. It can be divided into patients who have a failure of the thyroid gland to produce sufficient thyroid hormone (primary hypothyroidism) and patients in which pituitary or hypothalamic disease is associated with impaired TSH stimulation (central or secondary hypothyroidism). Worldwide, primary hypothyroidism is caused most often by iodine deficiency. In areas where iodine is sufficient, chronic autoimmune thyroiditis (Hashimoto s thyroiditis) accounts for most cases. Other causes include postpartum thyroiditis, surgical removal, or radioactive iodine ablation of the gland. Hypothyroidism present at birth (cretinism) is the most common preventable cause of mental retardation in the world. 

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