Iodine deficiency children

ADHD in iodine-deficient children could be due to an inadequate supply of maternal thyroid hormone... 

In humans, Murray and Pochin (1951) have confirmed that isotopic iodine from iodate is available to the thyroid when given per os, but the bioavailabifity was about 10% lower than that of iodide. Five milligrams of iodine weekly per os reduced goiter prevalence among iodine-deficient children equally well, whether given in the form of iodate or iodide tablets (Scrimshaw et al., 1953). However, this study does not prove exact bioequivalence of the two iodine compounds, since the iodine dose by far exceeded the physiological requirement, which might have obscured minor differences in bioequivalence. 

Iodine deficiency represents a major pubfic health problem in many countries in the Asia Pacific region. The World Health Organization (WHO) estimates that there are close to 1 billion people living in the southeast Asian and western Pacific regions, out of approximately 2 billion worldwide, who have urinary iodine excretion (UIE) less than the minimum level of 100 j,g/l (Table 127.1). As a consequence, it is speculated that mental and physical growth will be impeded in hundreds of millions of iodine-deficient children within this part of the world and they will not realize their full genetic potential because of dietary iodine deficiency. 

Before providing data from India, it is relevant to summarize the information from other countries recently making the transition from an iodine-deficient to an iodine-sufficient state. Studies from Greece, Turkey and Iran report an increase in the prevalence of antithyroid peroxidase antibodies in the population after iodine supplementation (Zois et ai, 2003 Bastemir et aL, 2006 Heydarian et ai, 2007). Interestingly, other studies have provided data to the contrary. For example, the introduction of iodized salt to severely iodine-deficient children did not provoke thyroid autoimmunity in a study conducted in Morocco (Zimmermann et ai, 2003). 

Iodine excretion and serum T4 are markedly lower in the iodine-deficient group than in the control group. The effects of treatment with Lipiodol are disappointing the mean urinary I before and after treatment is nearly the same and there is no difference in the frequency distributions. In each group more than half of the children are excreting less than 40 xg/L. The plasma T4 did not change either, with 19 Z of the treated children and 17 Z of the iodine-deficient children having values lower than 6 xg/dl. There is no difference between T4 mean values, or between frequency distributions. For a more detailed description of this study see Escobar del Rey et al. (33). 

A series of studies have evaluated the possible consequraces of transiait impairment of thyroid function during the neonatal period due to iodine deficiency. Studies conducted in areas with severe iodine deficiency have shown that there is a dramatic shift of the intellectual quotients (IQ) towards low values in schoolchildren bom to severely iodine deficient mothers. After the pioneer studies conducted in this field by the group of FIERRO-BENITEZ in Ecuador this concept has been confirmed by many others (Review in The same trend has also been illustrated in Europe BLEICHRODT et al. have showed that the frequency distribution of IQ in clinically euthyroid schoolchildren was also shifted towards low values in children from an iodine deficient area as compared to controls bom in the same type of rural villages but without iodine deficiency. This mental deficit was only partly corrected 32 months after the oral administration of iodized oil in the iodine deficient children. Consequently the deficit is due partly to hypothyroidism occurring in early life. Similar results were reported by others... 

Underwood BA, Loerch JD, Lewis KC (1979) Effects of dietary vitamin A deficiency, retinoic acid and protein quantity and quality on serially obtained plasma and liver levels of vitamin A in rats. JNutr 109 796-806 Centanni M, Maiani G, Vermiglio F, Canettieri G, Sanna AL, Moretti F, Trimarchi F, Andreoli M (1998) Combined impairment of nutritional parameters and thyroid homeostasis in mildly iodine-deficient children. Thyroid 8 155-159... 

In a review of 18 studies, a comparison was made between IQ scores in iodine-deficient children and carefully selected control groups. The iodine-deficient group had a mean IQ that was 13.5 points lower than that of the non-iodine-deficient control group. Detailed individual studies demonstrating these defects in Italian and Spanish schoolchildren as well as those from Africa, China, Indonesia, and Papua New Guinea have been published. There is a serious problem in Europe as well as in many developing countries. 

Figure 62.1 A mother and child from a New Guinea village who are severely iodine deficient. The mother has a large goiter and the ohild is also affeoted. The bigger the goiter, the more likely she will have a cretin child. This can be prevented by eliminating the iodine deficiency before the onset of pregnancy. Reproduced with permission from Hetzel and Pandav (1996).

DeLong, G.R., Stanbury, J.B. and Fierro-Benitez, R. (1985). Neurological signs in congenital iodine-deficiency disorder (endemic cretinism), Dev.Med Child Neurol 27, no. 3, pp. 317-324. 

Iodine deficiency affects the socioeconomic development of an afflicted community in other ways than its important physiological manifestations, viz., goiter, hypothyroidism, cretinism, reproductive failure, and child mortality, among others. The socioeconomic retardation of the affected community occurs in two ways. People are mentally slower and less vigorous, so it is harder to educate and motivate them, and thus they are less productive in their work. Besides, iodine deficiency produces more handicapped individuals who depend on others for their care, which in turn diverts the community resources. Secondly, in most of the areas, agriculture is the most important economic activity, and domestic animals suffer from iodine deficiency in much the same way as people do. Therefore, domestic animals are smaller in size and produce less meat, eggs and wool. They also suffer from abortion and are often sterile. 

In this project, lOCs were given to all WCBA and infants (0—2 years) as a transitional measure aimed at protecting the unborn child and young infants from the effects of iodine deficiency, while the ultimate goal is still for Tibet to catch up with the rest of the country in LJSI (Li et al, 2005). The IOC, coordinated by the TDOH and seven prefecture health bureaus, was distributed annually through the rural primary healthcare system at county,... 

Providing up-to-date information about the influence of iodine deficiency on fetus development during pregnancy, child growth and development. 

The population did not see any relationship between goiter and cretinism. The reduced inteUigence observed in cretins was not attributed to iodine deficiency. It is the child of a mother who was promiscuous or responsible... 

This is not the time to rest the efforts should be more vigorous now. The problem of IDD is stiU largely perceived as equivalent to goiter. People consider it a cosmetic problem and hence a low-priority issue. Focus should be more on the implications that iodine deficiency has on the IQ of the child and the contribution of elimination of IDD to at least six of the millennium development goals. 

We use iodized salt to prevent goiters and mental retardation. In China, a country of 1.2 billion people, there are 10 million cases of retardation from lack of iodine. Although just trace amounts would prevent this, many people buy noniodized salt on the black market to save money. Maternal iodine deficiency results in growth and brain impairment in the child. 

All this activity has stemmed from a new perception of the effects of iodine deficiency. The concept of the Iodine Deficiency Disorders refers to a broad spectrum of conditions which affect the fetus, the neonate, the child and the adult. Particularly important are the fetal effects, including miscarriage, stillbirth, as well as neurological cretinism which is of special interest to this symposium, as it is the reference point for studies on iodine and the brain. This condition, well known in the ancient and mediaeval worlds, was described in Diderot s Encyclopedie in 1754 when a cretin was defined as an "imbecile with a goitre down to the waist". 

This report pertains to (1) an iodine deficient (ID) cohort of children (n 519) who were born prior to the introduction of any iodine prophylaxis (2) a cohort of children (n-124) of variable iodine status (IV) who were born of mothers who had not been injected with iodized oil but had possibly used iodated salt by the time of the index child s conception, and (3) an iodine sufficient (IS) cohort of children (n-143) who were born of mothers who had been injected with iodized oil prior to the index child s conception. 

In children whose mothers had received iodized oil prior to the index child s conception (i.e. the IS cohort), there was complete prevention of cretinism, and there was also a reduction in their age at walking as compared to children whose mothers were iodine deficient throughout the index child s gestation (i.e. the ID cohort). 

Ibrahim M, de Escobar GM, Visser TJ, Duran S, van Toor H, Strachan J, Williams FL, Hume R. Iodine deficiency associated with parenteral nutrition in extreme preterm infants. Arch Dis Child Fetal Neonatal Ed 2003 88(1) F56-7. 

The present paper concerns the new dimension of understanding of the full spectrum of the effects of iodine deficiency on growth and development which include the effects of iodine deficiency on the fetus, the neonate, the child and adolescent, and the adult, with special reference to brain function (Table 1). 

My comment is in response to Dr. Laurberg s comment. There is an important difference between a hypothyroid child bom in an iodine deficient area and congenital hypothyroidism. Congenital hypothyroid children probably develop normally after birth, when given adequate thyroxine treatment, because their brain was selectively protected by maternal T4 until birth. On the contrary, in severely iodine deficient areas, the fetal brain cannot benefit from the same protection because of the low thyroxine levels in maternal serum. 

With regard to the remark of Dr. Koutras, I would like to stress the point that in areas with a moderate iodine deficiency, higher than normal TSH levels can be found in children. If one looks at large population samples in areas with iodine deficiency, the mean TSH levels are markedly higher than in control populations. This is not just a tendency TSH could be twice or even three times the values found in control populations. Moreover, if TSH levels are related to total T4 levels in the same subjects, it appears that to reach a given T4 level in one child requires a TSH stimulation several times higher than in adults. It is probable that the low intrathyroidal stores found in children are the cause of the increased stimulation necessary to achieve normal serum T4 levels. 

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