History of iodine deficiency and effects on hearing loss and IQ of children
The RDA established for iodine is based on the minimum daily amount needed to prevent goiter, supposedly 0.15 mg/day (150 mcg/day). Goiter is the enlargement of the thyroid in response to extremely low iodine intake.
Iodized salt is the government's mainstay for prevention of goiter, therefore anyone who is not using adequate amounts of iodized salt in his diet will most likely be deficient in iodine because iodine occurs in such small quantities in food. Even though the USA is considered an iodine-sufficient nation by the bureaucrats, the USA is not in the least bit iodine sufficient. First of all, less than 50% of Americans use salt in their diets, and of the 50% who do, only half of them use iodinized salt. So how could the others who are not using the main goiter preventative (iodinized salt) really be iodine sufficient? Furthermore iodine is not evenly distributed in iodinized salt, and even the entire 1 pound Morton salt container only has, supposedly, 37 mg of iodine. Dr. Brownstein recommends 50 mg/day of iodine, not the insignificant 0.15 mg/day. The coastal Japanese have been taking the equivalent of 100 mg/day of iodine for thousands of years in the form of kelp. They have far fewer chronic diseases and cancers than the Japanese (and non-Japanese) living in the USA.
Since the thyroid gland is the most effective iodine-trapping organ in the body, the appearance of a goiter will be one of the very last signs of iodine deficiency. Before a goiter occurs there will likely be many other signs and symptoms of iodine deficiency such as fibrocystic breast disease, ovarian cysts, skin problems, atherosclerosis, elevated cholesterol levels, decreased mental status, depression, and fatigue.
Acta Endocrinol (Copenh). 1990 Dec;123(6):577-90. Iodine deficiency diseases in Switzerland one hundred years after Theodor Kocher's survey: a historical review with some new goitre prevalence data.Bürgi H, Supersaxo Z, Selz B. Medizinische Klinik, Bürgerspital, Solothurn, Switzerland.
In certain regions of Switzerland, before prophylaxis, 0.5% of the inhabitants were cretins, almost 100% of schoolchildren had large goitres and up to 30% of young men were unfit for military service owing to a large goitre.
Iodization of salt was introduced in 1922 at 3.75 mg I per kg and the iodine content was doubled twice, in 1962 and 1980, to the present 15 mg I per kg. In 1988, 92% of retail salt and 76% of all salt for human consumption (including food industry) was iodized, even though its use is voluntary. Urinary iodine excretion, previously between 18 and 64 micrograms per day, has now risen to 150 micrograms per day. No new endemic cretins born after 1930 have been identified. Goitre disappeared rapidly in newborns and schoolchildren, more slowly in army recruits, and incompletely in elderly adults. In some Cantons (by constitution in charge of health matters and the salt monopoly) which allowed iodized salt only in 1952, disappearance of goitre lagged behind accordingly, proof that iodized salt was the cause of regression.
The Swiss data provide evidence that isolated deafness, mental deficiency, and short stature, each without the other attributes of cretinism have also decreased. Adverse effects of iodized salt were minimal, possibly because the initial iodine content of salt was chosen very low. Iodization of salt has proved a highly cost-effective preventive measure in Switzerland.
In view of the fact that, during the first period of life, thyroid hormones are critical for brain development, we investigated whether even transient congenital hypothyroidism could affect the long-term intellectual development of affected infants.
A case-control study of intellectual development, auxometric parameters and thyroid function performed in late infancy in children with documented transient congenital hypothyroidism or hyperthyrotrophinaemia at birth.
Nine children born in an endemic goitre area who had short-term transient congenital hypothyroidism or hyperthyrotrophinaemia after birth (TCH) were studied and compared to nine matched children born in the same area at the same time but having normal thyroid function at birth (N).
Global, verbal and performance IQs were evaluated on the Wechsler scale. Height, bone age, total and free thyroid hormones, thyroid volume, thyroglobulin, basal and TRH stimulated TSH were also measured.
Height and bone age were similar in the two groups. Thyroid function tests were also similar in the two groups except for basal and TRH stimulated serum TSH and serum Tg which were higher in the TCH than in the control group. Global, verbal and performance IQs were systematically lower in the TCH than in the N group. (78.3 +/- 11.1 vs 90.9 +/- 14.2, P < 0.05; 84.4 +/- 15.4 vs 96.2 +/- 14.8, P NS; 75.0 +/- 8.5 vs 89.2 +/- 12.5, P < 0.01 respectively).
Infants born and living in an academic goitre area, who had biochemical signs of thyroid hypo-function at birth, had a lower intelligence quotient at the age of 7-8 years than matched controls living in the same environmental conditions but with normal thyroid function at birth. The present findings strongly suggest that abnormalities in thyroid function at birth, even when transient, can adversely affect long-term intellectual development.
The effect of prolonged iodine deficiency on learning and motivation was studied. One hundred male children--matched for age, socioeconomic status, and formal education--were selected from both severely iodine-deficient (SID) and mildly iodine-deficient (MID) villages. Mean urinary iodine excretion was significantly lower in the SID than in the MID group (219.84 +/- 57.52 compared with 449.14 +/- 32.31 nmol/L, P < 0.001). The serum thyroxine concentration was significantly lower (90.36 +/- 6.46 compared with 123.70 +/- 15.42 nmol/L, P< 0.001) and serum thyroid-stimulating hormone (TSH) was significantly higher in the SID group than in the MID group (6.23 +/- 0.34 compared with 4.85 +/- 0.28 mU/L, P< 0.01). The children were administered maze, verbal, and pictorial learning tasks and a test of motivation. The results showed that SID children are slow learners compared with MID children. In both groups the rate of learning over trials was superior in younger (aged 9-12 y) children although the initial performance of older (aged 12-15 y) children was better (P < 0.01). SID children scored significantly lower than MID children on the achievement motivation scale (P < 0.01). The results are suggestive of neural impairment as well as poor sociopsychologic stimulation, resulting in learning disability and lowered achievement motivation. Unless iodine nutrition is improved in the community as a whole, these abnormalities may prevent millions of children from the SID areas from achieving their full potential even if learning opportunities are made available to them.
Severe iodine deficiency still occurs in many countries, and causes cretinism and mental impairment. In southern Xinjiang province, China, after usual methods of iodine supplementation had failed, we iodinated irrigation water to increase iodine in soil, crops, animals, and human beings. 5% potassium iodate solution, dripped into an irrigation canal for 12 or 24 days, increased soil iodine 3-fold, and crop and animal iodine 2-fold. Median urinary iodine excretion in children increased from 18 to 49 micrograms/L (two groups of similar age). The cost for iodine was US $0.05 per person per year. Soil iodine remained stable over one winter, and dripping of iodine during the second year (US $0.12 per person per year) resulted in a further 4-fold increase in soil iodine and a 1.8-fold increase in iodine in crops. We conclude that iodination of irrigation water is an advantageous and cost-effective method of supplying iodine in southern Xinjiang, and may be useful in other areas dependent on irrigation. Med Hypotheses. 2008 Nov;71(5):645-8. Iodine deficiency, more than cretinism and goiter. Verheesen RH, Schweitzer CM.Regionaal Reuma Centrum Z.O. Brabant, Máxima Medisch Centrum, Ds. Th. Fliednerstraat 1, 5631 BM, Postbus 90052, 5600 PD Eindhoven, The Netherlands. firstname.lastname@example.org
Recent reports of the World Health Organization show iodine deficiency to be a worldwide occurring health problem. As iodine status is based on median urinary iodine excretion, even in countries regarded as iodine sufficient, a considerable part of the population may be iodine deficient. Iodine is a key element in the synthesis of thyroid hormones and as a consequence, severe iodine deficiency results in hypothyroidism, goiter, and cretinism with the well known biochemical alterations. However, it is also known that iodine deficiency may give rise to clinical symptoms of hypothyroidism without abnormality of thyroid hormone values. This led us to the hypothesis that iodine deficiency may give rise to subtle impairment of thyroid function leading to clinical syndromes resembling hypothyroidism or diseases that have been associated with the occurrence of hypothyroidism. We describe several clinical conditions possibly linked to iodine deficiency, a connection that has not been made thus far. In this paper we will focus on the relationship between iodine deficiency and obesity, attention deficit hyperactivity disorder (ADHD), psychiatric disorders, fibromyalgia, and malignancies. (2588-8-11; 2657-8-13; 3150-8-23; 5500-10-12; 6230-10-28; 6875-11-11; 8326-12-15; 9392-01-09; 10146-01-25; 11199-02-15; 14667-04-15; 30924-11-20; 36465-01-03; 40884-02-07; 70905-10-03; 88401-3-2-14) Aloe may be helpful. HEARING LOSS: Iodine deficiency is common in America, Europe, New Zealand, and worldwide. Iodine “sufficiency” in a particular country only means that on average the population, but not each individual, has adequate iodine intake. Even mild iodine deficiency causes hearing loss in children. Adding iodine to the diet may correct hearing loss in children. -------------------------------------------------------- http://www.ncbi.nlm.nih.gov/pubmed/11128728 Thyroid. 2000 Nov;10(11):991-9. The auditory threshold in a school-age population is related to iodine intake and thyroid function. Soriguer F, Millón MC, Muñoz R, Mancha I, López Siguero JP, Martinez Aedo MJ, Gómez- Huelga R, Garriga MJ, Rojo-Martinez G, Esteva I, Tinahones FJ.
Endocrinology and Nutrition Service, Civil Hospital, Carlos Haya Hospital Complex, Malaga, Spain. email@example.com
Abstract The aim of this study was to determine the relationship between auditory capacity and urinary iodine, taking into account thyroid volume and function, in a population of schoolage children. Audiometry was carried out in 150 children (ages 6-14 years), together with measurements of thyroid volume, thyrotropin (TSH), free T3, free T4, thyroglobulin, antiperoxidase and anti-TSH receptor antibodies, as well as iodine in a casual urine sample. Children with a TSH >5 microU/mL were excluded from the study. In the children with palpable goiter, there was an inverse relation between the auditory threshold at all frequencies and ioduria. Children with thyroglobulin values >10 ng/mL had a higher auditory threshold at all frequencies. In the children with palpable goiter and ioduria <100 microg/L, the levels of thyroglobulin and ioduria and the age accounted for 75% of the decibel (dB) variance at 2000 (Hertz), with similar results at other frequencies. The children with a thyroid sized at the >95th percentile had an odds ratio of 3.86 (95% confidence interval: 2.59-5.10) of having a threshold >20 dB. The results warn that iodine prophylaxis is needed to prevent not only goiter but also other iodine-deficiency disorders, such as involvement of the auditory threshold in school-age children.
----------------------------------------------------------------------- http://www.ncbi.nlm.nih.gov/pubmed/11189164 Lin Chuang Er Bi Yan Hou Ke Za Zhi. 1998 May;12(5):228-30. [Iodine deficiency and perceptive nerve deafness]. [Article in Chinese] Gao H, Li J, Wang E. Department of Otorhinolaryngology, 414 Navy Hospital, Nanjing 210015.
Abstract Iodine contents (ICS) in hairs of 381 children with perceptive nerve deafness (PND) and in table salt were determined in Yancheng prefecture and Shuyang county of Jiangsu province, east China from 1995 to 1996. The results showed that the ICS in hairs of deaf children were much lower than that of healthy children (P < 0.01). And the ICS in table salt in these regions were under the standard content officially published. Presumably, iodine deficiency (ID) in these regions may be one of the major factors causing PND.
----------------------------------------------------------------------- http://www.ncbi.nlm.nih.gov/pubmed/16218041 J Endocrinol Invest. 2005 Jul-Aug;28(7):595-8. Effect of 10 yr of the iodine supplementation on the hearing threshold of iodine deficient schoolchildren. Azizi F, Mirmiran P, Hedayati M, Salarkia N, Noohi S, Rostamian D. Endocrine Research Center and Department of Medicine, Taleghani Medical Center, Shaheed Beheshti University of Medical Sciences, Tehran I.R., Iran. firstname.lastname@example.org
OBJECTIVE: Auditory disturbances may be present in iodine deficient children. The aim of this study was to determine the effect of long-term iodine supplementation on auditory thresholds in iodine deficient children.
DESIGN AND METHODS: 70, 70 and 72 schoolchildren of an area of severe iodine deficiency were studied before intervention (1989), 3 yr after injection of 480 mg iodized oil (1992) and 7 yr after consumption of iodized salt (1999), respectively. Goiter was graded and serum T4, T3, TSH and thyroglobulin concentrations and urinary iodine levels were measured. Audiometry was performed with a pure tone audiometer.
RESULTS: There was significant decrease in the prevalence and severity of goiter and serum TSH and thyroglobulin concentrations, and significant rise in serum T4 in 1992 and 1999, as compared to 1989. Before iodine supplementation, hearing was abnormal in 44% of schoolchildren, mean hearing threshold was 15.8 +/- 5.9 and in all children was >10 dB. Mean hearing threshold decreased to 10.2 +/- 4.6 and 10.0 +/- 5.9, 3 and 10 yr after intervention (p < 0.001). Forty seven and 62% of children had thresholds < 10 dB in 1992 and 1999, respectively. Hearing thresholds > 15 dB were detected in 46, 11 and 10% of schoolchildren in 1989, 1992 and 1999, respectively (p < 0.001).
CONCLUSION: Continuous iodine supplementation permanently improves the auditory thresholds of iodine deficient children.
------------------------------------------------------------------------ http://www.ncbi.nlm.nih.gov/pubmed/11528490 Eur J Clin Nutr. 2001 Sep;55(9):763-8. Mild iodine deficiency is associated with elevated hearing thresholds in children in Benin. van den Briel T, West CE, Hautvast JG, Ategbo EA. Division of Human Nutrition and Epidemiology, Wageningen University, Wageningen, The Netherlands.
OBJECTIVE: Elevated hearing thresholds have been demonstrated in populations afflicted by endemic cretinism as a result of severe iodine deficiency. However, data on the effects of less severe iodine deficiency on hearing thresholds in apparently normal children are scant. This study addresses the question whether there is a relationship among iodine variables, hearing and mental performance in a mildly iodine-deficient population.
DESIGN: A randomized, placebo-controlled intervention trial with an observation period of 11 months.
SETTING: An iodine-deficient area in northern Benin.
SUBJECTS: A total of 197 school children, aged 7-11 y.
INTERVENTIONS: A total of 97 children received an oral dose of iodized oil, containing 540 mg I, while 100 children received a placebo. About 3-4 months after supplementation, the whole population began to have access to iodized salt. Non-verbal mental tests were administered and biochemical indicators (thyrotropin, free thyroxine, thyroglobulin and urinary iodine) were measured at the beginning and the end of the study. Hearing was measured at the end of the study in both ears by pure-tone audiometry at seven frequencies.
RESULTS: In this mildly iodine-deficient child population children with higher serum thyroglobulin concentrations had significantly higher hearing thresholds in the higher frequency range (> or = 2000 Hz) than children with lower serum thyroglobulin concentration. Moreover children with lower hearing thresholds performed significantly better on the mental tests used.
CONCLUSIONS: Even when iodine deficiency is 'mild', promotion of adequate iodine intake through salt iodization programs and other means remains crucial.
------------------------------------------------------------------ http://www.ncbi.nlm.nih.gov/pubmed/11063446 Am J Clin Nutr. 2000 Nov;72(5):1179-85. Improved iodine status is associated with improved mental performance of schoolchildren in Benin. van den Briel T, West CE, Bleichrodt N, van de Vijver FJ, Ategbo EA, Hautvast JG. Division of Human Nutrition and Epidemiology, Wageningen University, Wageningen, Netherlands.
BACKGROUND: An adequate iodine supply in utero and shortly after birth is known to be crucial to an individual's physical and mental development. The question of whether iodine supplementation later in life can exert a favorable influence on the mental performance of iodine-deficient populations was addressed in various studies, but with contradictory results.
OBJECTIVE: The aim of this study was to examine the effect of an improvement in iodine status on mental and psychomotor performance of schoolchildren (7-11 y) who were moderately to severely iodine deficient.
DESIGN: The study, which was originally planned as a double-blind, randomized, placebo-controlled intervention, was carried out in an iodine-deficient population of schoolchildren (n = 196) in northern Benin. As the population began to have access to iodized salt during the 1-y intervention period, the study population was split post hoc-on the basis of urinary iodine concentrations-into a group with improved iodine status and a group with unchanged iodine status. Changes in mental and psychomotor performance over the intervention period were compared.
RESULTS: Children with increased urinary iodine concentrations had a significantly greater increase in performance on the combination of mental tests than did the group with no change in urinary iodine concentrations.
CONCLUSIONS: An improvement in iodine status, rather than iodine status itself, determined mental performance in this population, which was initially iodine deficient. These findings suggest a "catch-up" effect in terms of mental performance.
------------------------------------------------------------------- http://www.ncbi.nlm.nih.gov/pubmed/12848208 J Trop Pediatr. 2003 Jun;49(3):168-71. Prevalence and risk factors of iodine deficiency among schoolchildren. Gür E, Ercan O, Can G, Akkuş S, Güzelöz S, Ciftcili S, Arvas A, Iltera O. Department of Pediatrics, Cerrahpasa Medical Faculty, Istanbul University, Turkey.
The aim of this study was to demonstrate the prevalence of iodine deficiency among schoolchildren and the risk factors influencing it. One thousand five hundred and seventythree schoolchildren were chosen from 14 schools in seven different regions in Istanbul. After all data relating to sociodemographic factors and the use of iodized salt were recorded, iodine contents of urine samples were determined by the Sandell Kolthoff reaction. Chisquared and multiple regression analysis were used for the investigation of the correlation between iodine deficiency and risk factors. The prevalence of goitre (> or = 2 grade) was 1.9 per cent. The median urine iodine level was in the normal range (10.5 microg/dl). In 46.2 per cent of the students the urine iodine levels were below 10 microg/dl and 13.9 per cent of the students had urine iodine levels below 5 microg/dl. The prevalence of iodine deficiency was significantly higher in younger (< or = 10 years) children, in children with less educated mothers and fathers, and with poorer and more crowded families (p < 0.01, p < 0.01 and p < 0.01, p < 0.001, respectively). The rate of iodine deficiency was significantly higher in females than in males and also higher in children who lived on the European side of Istanbul than on the Anatolian side of Istanbul (p < 0.0001, p < 0.0001, respectively). The rate of use of iodized salt was 44.4 per cent and the iodine deficiency rate was not affected by the use of iodized salt (p > 0.05). Although the median urine iodine level was in the normal range, in 46.2 per cent of the students urine iodine levels were low (< 10 microg/dl). As there seems to be no effect from the use of iodized salt in iodine deficiency, the use of a more stable potassium iodate for the fortification of salt may be required.
--------------------------------------------------------- http://www.ncbi.nlm.nih.gov/pubmed/17016950 Food Nutr Bull. 2003 Dec;24(4 Suppl):S91-8. Iodine deficiency: consequences and progress toward elimination. Maberly GF, Haxton DP, van der Haar F. Department of International Health, Rollins School of Public Health, Emory University, Atlanta, Georgia 30322, USA. email@example.com
While traditionally associated with cretinism and goiter, iodine deficiency has broad effects on central nervous system development that can occur in the absence of either condition. Any maternal iodine deficiency results in a range of intellectual, motor, and hearing deficits in offspring. This loss in intellectual capacity limits educational achievement of populations and the economic prowess of nations. Progress made since the historic World Summit for Children in 1990 has been outstanding. Approximately 70% of households in the world used iodized salt by 2000, compared with less than 20% in 1990. It is estimated that at least 85 million newborns out of 130 million annual births are protected from a loss in learning ability that would otherwise have occurred. The elimination of iodine deficiency, by expedient production, marketing, and universal consumption of iodized salt, represents a significant development effort in public nutrition. Although globally iodine nutrition has greatly improved, 20% to 30% of pregnancies and thus newborns still do not fully benefit from the use of iodized salt. Countries where success is in evidence could rapidly revert back to deficiency if vigilance is not maintained. Just as success came through concerted publicprivate- civic actions, making sure that this is expanded and will steadily go on requires continuous collaboration.
------------------------------------------------------------ http://www.ncbi.nlm.nih.gov/pubmed/12192540 Eur J Nucl Med Mol Imaging. 2002 Aug;29 Suppl 2:S404-16. Epub 2002 Jun 1. Iodine deficiency in Europe and its consequences: an update. Delange F. International Council for Control of Iodine Deficiency Disorders, Department of Pediatrics, Hospital Saint-Pierre, University of Brussels, 153, avenue de la Fauconnerie, 1170 Brussels, Belgium. firstname.lastname@example.org
This paper updates the information on the prevalence of the disorders induced by iodine deficiency (IDD) in Europe. Thirty-two European countries were still affected by mild to severe iodine deficiency in the late 1990s. The most severely affected countries were in Eastern Europe, including Central Asia, but Western Europe was also still affected. National surveys recently conducted in 11 of these countries show that, with the exception of the Netherlands, none has yet reached a state of iodine sufficiency, though very significant improvement in the situation has been evidenced in many of them, e.g. Poland, Bulgaria and Macedonia. The consequences of persisting iodine deficiency are goitre, hyperavidity of the thyroid for iodide (which increases the risk of thyroid irradiation in the event of a nuclear accident) and subclinical hypothyroidism during pregnancy and early infant (with a concomitant risk of minor brain damage and irreversible impairment of the neuropsychointellectual development of offspring). Access to iodized salt at the household level in European countries affected by IDD increased from 5%-10% in 1990 to 28% in 1999. This constitutes encouraging progress. However, in terms of access of iodine-deficient countries to iodized salt, Europe remains the worst region in the world, as shown by the fact that the mean figure worldwide in 1999 was 68%. In Latin America it even reached 90%. Salt iodization has to be further implemented in Europe. Until that goal is achieved, iodine supplementation in those groups most sensitive to the effects of iodine deficiency (pregnant and lactating women and young infants) will have to be considered in the most severely affected areas.
------------------------------------------------- http://www.ncbi.nlm.nih.gov/pubmed/8200329 Eur J Clin Nutr. 1994 Jan;48(1):54-9. Relationship between urinary iodine concentration and hearing capacity in children. Valeix P, Preziosi P, Rossignol C, Farnier MA, Hercberg S. Institut Scientifique et Technique de la Nutrition et de l'Alimentation, CNAM, France.
Urinary iodine excretion was assessed in 1222 healthy children aged 10 months (n = 456), 2 years (n = 368) and 4 years (n = 398) living in the Paris area and originating from continental France (55.2%), North Africa (15.7%), the West Indies (9.7%), West Africa (8.2%), Southeast Asia (5.5%), and southern Europe (5.7%). Iodine excretions (median values) were, respectively, 18.1, 13.4 and 11.6 micrograms/100 ml at 10 months, 2 years and 4 years, and risk of mild to moderate iodine deficiency (< 10 micrograms/100 ml) was 18.0%, 32.3% and 37.2% for the same age groups. Urinary iodine excretion was highest among Southeast Asian children, and lowest among West Africans. Hearing acuity was measured either by conventional mono-aural pure-tone audiometry or by binaural free field testing depending on the child's age. Hearing loss at 4000 Hz and average hearing impairment at speech frequencies (500, 1000 and 2000 Hz) were more severe among children at risk of mild to moderate iodine deficiency (less than 10 micrograms/100 ml) compared with those with urinary excretion above 10 micrograms/100 ml.
------------------------------------------------------------- http://www.ncbi.nlm.nih.gov/pubmed/1375063 Biol Trace Elem Res. 1992 Jan-Mar;32:259-66. Iodine intakes assessed by urinary iodine concentrations in healthy children aged ten months, two years, and four years. Valeix P, Preziosi P, Rossignol C, Farnier MA, Hercberg S. Institut Scientifique et Technique de la Nutrition et de l'Alimentation, CNAM, Paris.
Urinary iodine excretion was assessed in 642 healthy children aged 10 mo (n = 243), 2 yr (n = 183), and 4 yr (n = 216) living in the Paris area and originating from continental France (60.3%), North Africa (13.8%), the West Indies (9.1%), West Africa (8.3%), Southeast Asia (4.8%), and southern Europe (3.8%). Mild impairment of neurological (reflexes, tone, audiometry) and intellectual development (Brunet-Lézine scale) was assessed in relation to iodine status. Iodine excretions (median values) were 18.4, 11.9, and 10.9 micrograms/100 mL at 10 mo, 2 yr, and 4 yr, respectively, and risk of mild iodine deficiency (5-10 micrograms/100 mL) was 18.1%, 34.8%, and 38.3% for the same age groups. No relationship was found between anthropometry, global development quotient, and iodine status. High hearing thresholds were more commonly associated with lower iodine excretion, suggesting mild hearing defects. In spite of iodine prophylaxis, the risk of mild to moderate iodine deficiency still exists in France and in a number of European countries. Evaluation of neurological sequels of borderline iodine status is a major public health problem in European communities.
------------------------------------------------------------ http://www.ncbi.nlm.nih.gov/pubmed/12829349 Arch Pediatr. 2003 Feb;10(2):96-101. [Iodine nutritional status and risk factors for iodine deficiency in infants and children of the french North department]. [Article in French] Pouessel G, Bouarfa K, Soudan B, Sauvage J, Gottrand F, Turck D. Unité de gastro-entérologie, hépatologie et nutrition, clinique de pédiatrie, hôpital Jeannede-Flandre, 2, avenue Oscar-Lambret, 59037 Lille cedex, France.
INTRODUCTION: Iodine deficiency is responsible for a higher mortality and morbidity in neonates and infants. It has not yet disappeared in European countries, especially in Southern and Eastern Europe.
OBJECTIVES: The present study aimed at evaluating the status of iodine nutrition of infants living in the North department (France) and at studying risk factors for iodine deficiency.
METHODS: The study was conducted in primary health care centres in 160 healthy infants aged ten days to six years (mean +/- SD: 17.7 +/- 2.5 months). Data included: familial thyroid disease history, type of feeding at inclusion, timing of introduction of complementary foods, nutritional status (weight, height, head and arm circumference), as well as maternal education level and family socio-economical status. Iodine status was assessed by urinary iodine excretion.
RESULTS: Urinary iodine concentration ranged from 4 to 1042 microg/l (median +/- SD: 195,5 +/- 21,6 microg/l). Thirty-eight (24%) of 160 children were iodine deficient (urinary iodine < 100 microg/l): mild iodine deficiency (50-99 microg/l: 17%), moderate iodine deficiency (20-49 microg/l: 5%), severe iodine deficiency (<20 microg/l: 2%). No relationship was found between iodine status and age, , geographic origin of the children, as well as social and occupational group of the parents. Breast-feeding did not prevent from iodine deficiency. Iodine status did not differ between the cow's milk fed group and the group that was not fed cow's milk. Formula feeding was associated with iodine deficiency (p = 0,02).
CONCLUSIONS: Prevalence of severe iodine deficiency was very low in this population. However, iodine status was not optimal.
-------------------------------------------------------- http://www.ncbi.nlm.nih.gov/pubmed/15797674 Nutrition. 2005 Mar;21(3):325-31. Are breast-fed infants and toddlers in New Zealand at risk of iodine deficiency? Skeaff SA, Ferguson EL, McKenzie JE, Valeix P, Gibson RS, Thomson CD. Department of Human Nutrition, University of Otago, Dunedin, New Zealand.
OBJECTIVE: This study assessed the iodine status of New Zealand infants and toddlers and explored factors that might influence their iodine status.
METHODS: A community-based, cross-sectional survey of 6- to 24-mo-old children was conducted in three cities in the South Island of New Zealand. Iodine status was determined by a casual urine sample. Breast-feeding mothers were asked to provide a breast milk sample for iodine determination. Caregivers collected a 3-d weighed diet record from their children to investigate associations between dietary patterns and urinary iodine excretion.
RESULTS: The median urinary iodine concentration for the group (n = 230) was 67 microg/L (interquartile range 37-115) with 37% (95% confidence interval 30.5-43.4) of children having a urinary iodine concentration lower than 50 microg/L. When children were classified by current feeding method, those children who were currently formula-fed had a significantly higher median urinary iodine concentration (99 microg/L) than did children who were currently breast-fed (44 microg/L; P < 0.000). The mean iodine concentration in breast milk was 22 microg/L (n = 39). After multivariate analysis using estimates from 3-d diet records, only percentage of energy from infant formula was significantly associated with urinary iodine concentration (P = 0.005).
CONCLUSIONS: This study found mild iodine deficiency in a group of New Zealand infants and toddlers. Children who consumed infant formula, which is fortified with iodine, had better iodine status than did children who were currently breast-fed because breast milk contained low levels of iodine.
--------------------------------------------- http://www.ncbi.nlm.nih.gov/pubmed/2733614 Med J Aust. 1989 Jun 19;150(12):676-82. Iodine deficiency impairs intellectual and neuromotor development in apparently normal persons. A study of rural inhabitants of north-central China. Boyages SC, Collins JK, Maberly GF, Jupp JJ, Morris J, Eastman CJ. Westmead Hospital, NSW 2145.
Intelligence was measured by means of the Hiskey-Nebraska Test of Learning Aptitude or the Griffiths Mental Development Scales in a sample of 369 patients from iodine-deficient rural villages (Baihuyao), iodine-sufficient rural villages (Huanglo) and urban populations to test for the damaging effects of iodine deficiency on the development of the nervous system in the presumed healthy section of a community. In urban school-children who were aged seven to 14 years (n = 78), a normal range of measured intelligence was found (mean +/- SD intelligence-quotient score, 107.0 +/- 18.3). By comparison, intelligence-quotient scores were lower in all rural cohorts (a rural suppression effect) but the distribution of intelligence-quotient scores showed a further shift to the left in the iodine-deficient township. In Baihuyaon villagers who were aged 30-35 years (n = 50), who were born during the period of severe iodine deficiency, 72% of villagers had an intelligence-quotient score of less than 70 compared with 41% (P less than 0.05) of villagers who were aged 28-35 years from Huanglo, a rural iodine-sufficient control group (n = 49). Although measured intelligence was higher in Baihuyaon children whose mothers had received iodized salt - 44% of seven- to 14-year-old children had intelligence-quotient scores of less than 70 (n = 141)--it remained significantly depressed compared with rural (n = 51) and urban (n = 78) control subjects (18% and 4%, respectively). These findings were consistent with other parameters (that is, the persistently-high rate of goitre), which indicated that the saltiodization programme was inadequate. In the iodine-deficient village, lower intelligence quotient scores showed a relationship with the detection by audiometry of nerve deafness and with the presence of abnormal neurological signs. The latter included spasticity and pyramidal signs which were of a similar pattern to the neurological deficits that have been demonstrated in overt neurological cretins. We conclude that iodine deficiency imposes a further suppressive effect on the intellectual performance of rural inhabitants, and results in a shift of the entire population distribution of cognitive skills to a lower level.