Congenital hypothyroidism due to iodine deficiency is the most common preventable cause of mental retardation in the world. Iodine is not produced by our bodies so it must become an essential part of our diet. Iodine deficiency can lead to enlargement of the thyroid, hypothyroidism and to mental retardation in infants and children whose mothers were iodine deficient during pregnancy or when breastfeeding.
Why do we have a problem in Australia?
Australian nutrition surveys show that inadequate intake of foods from the key food groups is widespread in the Australian community (Markovic & Natoli 2009).
Gunton et al (1999) and colleagues implicate a combination of factors leading to a decline in our iodine intake.
For over three decades we have been dependent on iodine in milk contaminated by cleaning solutions (iodophors) used in the dairy industry; these solutions are gradually being replaced by others which leave less iodine in milk.
Using less iodised salt, through a combination of purchasing uniodised salt for consumption, decreasing our salt consumption (health messages)
Consuming most of our salt (uniodised) in processed foods.
40 per cent of pregnant women in studies carried out by Professor Robert Hume (Professor of Developmental Medicine, Division of Maternal & Child Health Sciences, University of Dundee) had less than half the recommended intake of iodine. Iodine Deficient Disorder affects 50 million children. 1.6 billion people are at risk. (Date: International Council of The Control of Iodine Deficiency Disorders).
Importance of iodine in pregnant and breastfeeding mothers
The thyroid hormone in adults is primarily responsible for regulation of our metabolism. In pregnant and breastfeeding mothers iodine is essential for developing embryo’s brain.
The thyroid gland is the first endocrine gland to develop in the embryo. It begins to form approximately 24 days after fertilisation often before a woman realises she is pregnant. As the embryo and tongue grow the developing thyroid descends in the neck. By 7 weeks the thyroid gland has assumed its definitive shape and has reached its final site in the neck. During the 11th week the synthesis of thyroid hormones occur. These hormones have an essential role in the development of the brain or central nervous system during the prenatal stage thus the importance of iodine in the mother’s diet. Deficiency in the mother’s diet will affect different areas of the growing embryo’s brain such as the cerebral cortex, inner ear, and other brain related functions which affect emotion, learning ability and memory. The defects in those anatomical regions produce different clinical manifestations.
Deficiencies in the mother
Adverse outcomes associated with Hypothyroidism can be seen as hypertension, pre-eclampsia, anaemia, post partum haemorrhage and cardiac – ventricular dysfunction.
Impact on the baby in utero
Hypothyroidism may also cause spontaneous abortion, fetal death, low birth weight and abnormal brain development.
Deficiencies in the developing embryo
In the cerebral cortex, a deficiency of iodine will cause an improper formation in association areas important for correct thinking processes. Iodine deficiency may cause malformations in the inner ear specifically in the cochlea producing deafness. It may also cause lack of development in the basal ganglia and cerebrospinal motor systems lead to spasticity, rigidity and slow movements. Problems could be observed in higher associative functions like language and abstract thought. In the case of babies/children with symptoms similar to autism there could be a defect in the development of deep areas of brain.
Signs and Symptoms of hypothyroidism in babies
Hypothyroidism occurs in about 26 babies each year in NSW/ACT. Early diagnosis is essential through new born screening. Some of the signs and symptoms for hypothyroidism in babies is prolonged gestation, increased birth weight, and open posterior fontanel, prolonged jaundice, decreased activity levels/lethargy, hoarse cry, poor feeding and feeding problems, noisy respiration, delayed stools at birth, constipation, dry skin and hypothermia.
Deficiencies in babies and young children
Untreated infants often display significantly low IQ due to mental retardation. They may have neurological problems such as gross and fine motor coordination, ataxia, altered muscle tone, deceased attention span and speech problems. Iodine deficiency can also cause permanent brain damage, mental retardation, deaf mutism, spasticity, and short stature.
Deficiencies in older children and adolescents
Iodine deficiency in older children and adolescents may cause cardiac problems, gastroperesis, delayed puberty, anovulation and infertility, insulin resistance and increased levels of total cholesterol.
Thyroxine tablets are crushed before administering to a baby. The sooner the treatment is commenced the less the impact on the neurological system. Regular tests will determine the correct thyroxine dose as the dose needs to be according to the child’s growth.
The recommended iodine intake
Pregnant and lactating women
· Daily iodine intake of 250 µg for pregnant and lactating women (The World Health Organization)
· 0 - 6 months: 110 micrograms per day (mcg/day)
· 7 - 12 months: 130 mcg/day Children
· 1 - 3 years: 90 mcg/day
· 4 - 8 years: 90 mcg/day
· 9 - 13 years: 120 mcg/day
· 150 µg
It is not recommended to add salt to the diet of a child’s under the age of 3 years of age.
Natural forms of Iodine
Iodized salt (table salt with iodine added is the main food source of iodine as ¼ teaspoon contains 95 micrograms of iodine). Seafood including shellfish is naturally rich in iodine (6-ounce portion of ocean fish provides 650 micrograms of iodine). Kelp (seaweed) is a rich source of iodine. Cheese, fish, eggs, soy milk, soy sauce also contain iodine as does some breads. Other good sources are plants grown in iodine-rich soil. Or multivitamins containing Iodine – MYADEC 150 µg.
This articel was provided by: Dr. Janet Green, RN, PhD Senior Lecturer, Coordinator of PG programs in neonatal and paediatric nursing, Faculty of Nursing, Midwifery and Health. University of Technology, Sydney
Cradle 2 Kindy Can Help
Find out how we can provide professional guidance to help you raise your children through our e-books, coaching and video courses.
All articles on this website have a copyright. The use of any material must have permission from Cradle 2 Kindy Parenting Solutions.
Disclaimer: Article on our website are for education purposes only. Please consult with your doctor to make sure this information is right for your child.