The thyroid gland, located in the base of the neck, absorbs iodine from the blood and uses this to produce hormones that regulate many body functions, including growth, nerve function, and absorption of vitamins and calcium. If the thyroid gland does not receive enough iodine from the blood, the gland may enlarge, causing a goiter. A goiter can also develop if the thyroid gland does not produce enough thyroid hormones, a condition called hypothyroidism. Goiter is also present in hyperthyroidism, when the gland produces too much thyroid hormone.
A common cause of goiter around the world is lack of iodine in the diet. The thyroid needs iodine to produce thyroid hormones, and if sufficient iodine is not available, the gland enlarges because it is working harder. The main dietary sources of iodine are grains and vegetables grown in iodine-rich soil, and saltwater fish and seafoods. The Recommended Daily Allowance (RDA) for iodine for adolescents and adults is 150 micrograms per day. To combat iodine deficiency in the U.S., iodine has been added to salt since 1924. The body needs only very small amounts of iodine for healthy thyroid function, so iodized salt usually provides an adequate dietary amount.
There are two forms of thyroid disorder, however, that affect children regardless of diet. Congenital hypothyroidism is a disorder in which a child may be born with an underactive thyroid gland. Symptoms appear when the baby is six to twelve weeks old, and include cool, mottled or yellowish skin, coarse hair, and a dull appetite. The baby's neck will look unusually short and fat. The facial features are also affected: the bridge of the nose is underdeveloped, so the nose appears flat and the eyes seem widely spaced, and the tongue is thick and protrudes.
Hypothyroidism slows the baby's growth and development, and the child may have weak muscles and slow reflexes. If untreated, this condition can lead to mental retardation . Hypothyroidism can also begin later in life, in a child born with normal thyroid function. It usually begins when a child is between 11 and 14 years old. Onset of this disease is not related to diet, but it may be a side effect of an auto-immune disease that attacks the thyroid. Children with this disease may develop dry, coarse hair and skin, poor circulation, and low blood pressure. Goiter may appear, along with the facial characteristics of the hypothyroid baby. The disease slows the child's growth, and puberty is usually delayed. All the symptoms of acquired hypothyroidism can be treated with medical intervention, and the condition does not lead to mental retardation. Diagnosis is made with a simple blood test, and treatment involves replacing the deficient thyroid hormones. The goiter may need to be removed surgically.
Hyperthyroidism, or overproduction of thyroid hormones, usually affects older women, and only rarely affects children. In children with this condition, goiter may develop, and the eyes may bulge out. Just the opposite of hypothyroidism, the hyperthyroid child grows faster than normal and may have flushed, warm skin, and increased heart rate. The child may be restless and irritable, unable to concentrate, and tire easily. All these symptoms can be reversed by medical treatment. Treatment usually involves medication that blocks the excess hormone production. Surgery may be needed to remove the thyroid gland or reduce its size.
The symptoms of thyroid malfunction are usually obvious, and can be confirmed with a blood test. Pediatricians normally keep careful records of a child's growth and weight gain, and can use these to diagnose the slowed or increased growth symptomatic of thyroid disease. Any swelling on a child's neck should be given prompt medical attention. Treatment of thyroid problems, especially if undertaken promptly, are usually successful and without serious side effects.
Examples of iodine-rich foods
|Food||Serving size||Micrograms of iodine|
|Cod or haddock, cooked||3-1/2 oz (100 g)||175|
|Chocolate milkshake (fast food)||1 average||158|
|Homemade meatloaf||3-1/2 oz (100 g)||123|
|Lima beans, boiled||1/2 cup (90 g)||104|
|Chocolate ice cream||1 cup (133 g)||94|
|Corn grits, cooked||1/2 cup (120 g)||86|
|Chocolate milk, low-fat||1 cup (250 g)||83|
|Yogurt, low-fat||1 cup (227 g)||73|
|Milk, low-fat||1 cup (244 g)||66|
|Milk, skim||1 cup (246 g)||64|
|Milk, whole||1 cup (244 g)||61|
For Your Information
- Bayliss, Richard I. S., and W. M. G. Tunbridge. Thyroid Disease: The Facts. New York: Oxford University Press, 1991.
- Wood, Lawrence C., David S. Cooper, and E. Chester Ridgway. Your Thyroid: A Home Reference. 3rd ed. New York: Ballantine Books, 1995.
- Zamula, Evelyn. "Thyroid Disorders Often Unsuspected." FDA Consumer 26, December 1992, pp. 34-39.
Gale Encyclopedia of Childhood & Adolescence. Gale Research, 1998.