Secondary Hypothyroidism

The thyroid gland is a small but very important gland of our body’s endocrine system. This gland normally weighs less than one ounce and lies along the windpipe at the base of the neck. It has two butterfly-shaped halves called lobes that are joined by a narrow band of tissue. This gland produces two long-acting chemicals known as thyroid hormones – thyroxine (T4) and triiodothyronine (T3). These hormones circulate throughout our bodies in the blood and are responsible for the normal functioning of all our body’s organs. In fact, every cell in our bodies depend upon thyroid hormones to regulate their metabolism.

In secondary hypothyroidism, not only is the thyroid involved, but also other endocrine system glands. The thyroid itself is regulated by another gland that is in the brain called the pituitary. In turn, the pituitary is regulated in part by the thyroid (via a “feedback” effect of thyroid hormone on the pituitary gland) and by another gland called the hypothalamus. The hypothalamus releases a hormone called thyrotropin (TRH), which sends a signal to the pituitary to release thyroid stimulating hormone (TSH). In turn, TSH sends a signal to the thyroid to release thyroid hormones (T4 and T3). If any of these hormone signals are interrupted, a defect in thyroid hormone production will result in a deficiency of thyroid hormone causing secondary hypothyroidism.

Children who have secondary hypothyroidism will have the following symptoms:

Early Symptoms

• Weakness;
• Fatigue;
• Cold intolerance;
• Constipation;
• Weight gain;
• Depression;
• Joint or muscle pain;
• Thin, brittle fingernails;
• Thinning of hair; and
• Pale color.

Late Symptoms

• Slow speech;
• Dry flaky skin;
• Thickening of the skin;
• Puffy face, hands and feet;
• Decreased taste and smell;
• Thinning of eyebrows;
• Hoarseness; and
• Menstrual disorder.

Children that show the symptoms described above should be examined by a special doctor called a pediatric endocrinologist to be tested for secondary hypothyroidism. Regular examinations, testing, and early treatment will prevent the damage caused by this condition.

Children who have hypothyroidism due to a pituitary or hypothalamus gland problem should take thyroid hormone replacement. Sometimes children with secondary hypothyroidism have problems with other endocrine glands, such as the adrenal gland. One of the effects of taking hormone replacement is an increased metabolic rate. This can trigger a severe or even life-threatening condition called addisonian (adrenal) crisis. Because of this possible condition, your child should be examined frequently by a special doctor called a pediatric endocrinologist. Before beginning hormone replacement therapy, the pediatric endocrinologist should perform a test that stimulates the release of adrenal hormones. If not enough adrenal hormone is present, in most cases, before hormone replacement therapy begins, children are treated with cortisone acetate, a stress hormone similar to the adrenal hormone.

Children with secondary hypothyroidism require hormone replacement therapy all their lives. If this therapy is stopped, symptoms will begin again. The medication given by your child’s doctor must be given even if symptoms stop. With early diagnosis and life-long treatment, your child will have a normal, healthy life.