The Fetus

Iodine deficiency of the fetus is the result of iodine deficiency in the mother (Figure 2). The condition is

Table 1 Spectrum of Iodine Deficiency Disorders

Fetus

Abortions

Stillbirths

Congenital anomalies

Neurological cretinism

Mental deficiency, deaf mutism, spastic

diplegia, squint

Hypothyroid cretinism

Mental deficiency, dwarfism,

hypothyroidism

Psychomotor defects

Neonate

Increased perinatal mortality

Neonatal hypothyroidism

Retarded mental and physical development

Child and

Increased infant mortality

adolescent

Retarded mental and physical development

Adult

Goiter with its complications

Iodine-induced hyperthyroidism

All ages

Goiter

Hypothyroidism

Impaired mental function

Increased susceptibility to nuclear radiation

Reproduced with permission from Oxford University Press and the World Health Organization, WHO/UNICEF/ICCIDD (2001).

Reproduced with permission from Oxford University Press and the World Health Organization, WHO/UNICEF/ICCIDD (2001).

associated with a greater incidence of stillbirths, abortions, and congenital abnormalities, which can be prevented by iodization.

Another major effect of fetal iodine deficiency is the condition of endemic cretinism, which is quite distinct from the condition of sporadic cretinism or congenital hypothyroidism due to a small or absent thyroid gland.

Endemic cretinism-associated with an iodine intake of less than 25 mg per day, in contrast to a normal intake of 100-150mgperday, has been widely prevalent, affecting up to 10% of populations living in severely iodine-deficient regions in India, Indonesia, and China. In its most common form, it is characterized by mental deficiency, deaf mutism, and spastic diplegia (Figure 3). This form of cretinism is referred to as the nervous or neurological type, in contrast to the less common hypothyroid or myxedematous type characterized by hypothy-roidism with dwarfism (Figure 4).

In addition to Asia, cretinism also occurs in Africa, (Zaire, now the Republic of the Congo), South America in the Andean region (Ecuador, Peru, Bolivia, and Argentina), and the more remote areas of Europe. In all these areas, with the exception of the Congo, neurological features are predominant. In the Congo, the hypothyroid form is more common, probably due to the high intake of the root vegetable cassava, which contains substances inhibiting the function of the thyroid gland.

However, there is considerable variation in the clinical manifestations of neurological cretinism,

Figure 3 A mother with her four sons, three of whom (ages 31, 29, and 28 years) are cretins born before iodized salt was introduced, and the fourth is normal (age 14years), born after iodized salt became available in Chengde, China. (Reproduced from Hetzel BS and Pandav CS (eds.) (1996) SOS for a Billion: The Conquest of Iodine Deficiency Disorders, 2nd edn. Oxford: Oxford University Press.)

Figure 3 A mother with her four sons, three of whom (ages 31, 29, and 28 years) are cretins born before iodized salt was introduced, and the fourth is normal (age 14years), born after iodized salt became available in Chengde, China. (Reproduced from Hetzel BS and Pandav CS (eds.) (1996) SOS for a Billion: The Conquest of Iodine Deficiency Disorders, 2nd edn. Oxford: Oxford University Press.)

Figure 4 A hypothyroid cretin from Sinjiang, China, who is also deaf mute. This condition is completely preventable. (Right) The barefoot doctor of her village. Both are approximately 35 years old. (Reproduced from Hetzel BS (1989) The Story of Iodine Deficiency: An international Challenge in Nutrition. Oxford: Oxford University Press.)

Figure 4 A hypothyroid cretin from Sinjiang, China, who is also deaf mute. This condition is completely preventable. (Right) The barefoot doctor of her village. Both are approximately 35 years old. (Reproduced from Hetzel BS (1989) The Story of Iodine Deficiency: An international Challenge in Nutrition. Oxford: Oxford University Press.)

which include isolated deaf mutism and mental defect of varying degrees. In China, the term cretinoid is used to describe these individuals, who may number 5-10 times those with overt cretinism.

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