Thyroid Trouble in Children

Excerpted from
Your Thyroid: A Home Reference
By Lawrence C. Wood, M.D., David S. Cooper, M.D., E. Chester Ridgway, M.D.

If your child's thyroid is not working properly, it is likely to have different effects than if you had the same problem. This is because your child is growing and developing, and growth and development can be changed by a thyroid that is either overactive (hyperthyroid) or underactive (hypothyroid).

In addition, thyroid trouble can be more difficult to recognize in a child than in an adult. Children are less likely to complain of feeling sick or to ask for help. They do not know what "normal" is, so even older children may simply accept the emotional and physical symptoms of a thyroid problem as "normal" for them. Therefore, it's usually up to someone else to recognize thyroid diseases when they occur in children. Indeed, an increase in irritability or hyperactivity noticed by a parent, friend or teacher, or a change in growth rate noted by a parent or pediatrician, may be the clue that leads to the discovery of a thyroid problem in a child.

Finally, since some thyroid disorders are inherited-passed on from one generation to the next-we would like to stress one very important point: If someone in the family has thyroid trouble now or has had a thyroid problem in the past, be sure to tell your child's physician about it. If it is the type of thyroid trouble that can be inherited, you will have alerted the physician to be watchful for that problem in your child. Any time the thyroid grows larger than normal, it is called a goiter. A goiter may appear at any age but is especially common in girls about the time their menstrual cycles begin.

If your child develops a goiter, it is possible that the child is still healthy and no important thyroid problem exists. On the other hand, most goiters that appear in children over six years of age are caused by low-grade inflammation of the thyroid gland known as chronic lymphocytic thyroiditis or Hashimoto's disease. In adults, this condition is a common cause of thyroid failure. Occasionally, a goiter may be the first sign of some other thyroid problem: for example, your child's thyroid may be overactive, or it may be enlarged as a result of a thyroid nodule within the gland.

Therefore, if you notice a goiter in your child, you should take the child to a physician for a checkup. By examining the child and obtaining a blood test, the doctor can tell whether the thyroid gland is overactive or underactive. Either of these thyroid conditions may interfere with a child's growth and development, but treating them will correct the thyroid hormone level and restore the growth pattern to normal.

Even if the results of the examination and the thyroid tests in a child with a goiter are normal, that does not mean necessarily that the goiter can be ignored. Rather, the physician will probably reexamine and retest your child at a later time to be sure a change in thyroid function has not occurred.

Rarely, a child's neck will have a swelling that appears to be a generalized enlargement of the entire thyroid gland but may actually be caused by an enlarged overlying fat pad or by growth of one or more lumps or nodules in the thyroid. The enlarged fat pad, which can be recognized by the fact that it does not move up and down with the Adam's apple when the child swallows, is of no significance. In the case of nodules, however, medical evaluation, as outlined later in this chapter, is very important and should be carried out promptly. Although most nodules prove to be harmless cysts or benign tumors, occasionally they contain thyroid cancer or reflect a change of thyroid function. Such conditions can and should be treated.

The Overactive Thyroid in Infancy And Childhood

One of the best-understood forms of thyroid trouble in children is the increased thyroid activity that affects some newborn babies and is known as neonatal hyperthyroidism. This condition is rare, occurring only in infants born of mothers with hyperthyroidism caused by Graves' disease. It is due to the passage of chemical substances called thyroid stimulators from the mother's blood across the placenta to her unborn baby. When these substances get into the baby's bloodstream, they may cause the baby's thyroid to make too much thyroid hormone.

Fortunately, this type of hyperthyroidism in a newborn baby lasts only as long as the mother's thyroid stimulators remain in the baby's bloodstream-usually from three to twelve weeks. Moreover, the condition is usually mild, since most women with an overactive thyroid do not have very high blood levels of the thyroid stimulators. Occasionally, a mother will have such high levels of the stimulators that her baby will be born with prominent eyes, irritability, flushing of the skin, and a fast pulse-all characteristics of an overactive thyroid at any age. In addition, these babies may have tremendous appetites but not gain weight. A goiter is common but may not be obvious at birth.

In its mildest form, this disease may require no treatment and will subside by itself in time. However, if the baby is seriously ill, treatment with iodine and an antithyroid drug such as propylthiouracil may be required to control the overactive thyroid gland. If more rapid control of symptoms is required treatment with a beta-adrenergic blocking drug like atenolol or propranolol may be helpful. The drug works by blocking the action of the high thyroid hormone levels on the baby's body. Thyroid surgery is rarely if ever needed, even if the baby has a very large thyroid because treatment with iodine usually causes the gland to shrink rapidly in size. This is fortunate, since a thyroid operation would be extremely difficult in so tiny a patient. Treatment can usually be discontinued in a few weeks, since the mother's thyroid stimulators soon disappear from the baby's bloodstream.

Even though this condition is extremely rare, a pregnant woman who has hyperthyroidism or who has been hyperthyroid in the past should alert the obstetrician about her thyroid problem during the pregnancy so that her doctor will be prepared to look for a thyroid abnormality in the baby.

Hyperthyroidism that occurs in children after the newborn period is very much like hyperthyroidism in adults. However, children generally do not complain of such things as having too much energy or feeling nervous, so it may be hard to tell that your child is sick with an overactive thyroid, even though you may be exhausted by a hyperactive and restless child who never seems to need a nap (Figure 12-1). Quite often the only clue that a problem exists will be a sudden growth spurt that makes a child with an overactive thyroid suddenly grow taller. A pediatrician who keeps careful records of the child's body measurements may notice such a change, but more often parents become aware of a sudden increase in growth when their child rapidly outgrows new clothes.

There are other clues by which we can recognize hyperthyroidism. Virtually all hyperthyroid children have a goiter and prominent eyes. Other common signs of thyroid overactivity include a rapid pulse, nervousness, increased sweating, and a dislike for hot weather. Parents may notice a deterioration of school performance, and the teacher may report that the child doesn't pay attention in class. Rapid growth of fingernails may lead to accumulation of dirt under irregular nail margins. Shaky hands may cause clumsiness and poor handwriting, and weak shoulder and thigh muscles may be apparent in play or sports. Emotional disturbances may be seen, and parents commonly note that even a gentle reprimand brings forth a flood of tears.