Individuals with Down syndrome have a higher incidence of endocrine problems than the general population. The endocrine system refers to a set of glands that include the thyroid, adrenal and pituitary glands.

What is hypothyroidism?

Hypothyroidism results from a malfunctioning thyroid gland, which decreases the synthesis of the hormone thyroxin. Thyroxin is the hormone that promotes growth of the brain and other body tissue.

How common is hypothyroidism?

Hypothyroidism is the most common endocrine problem in children with Down syndrome. It is estimated that approximately 10 percent of children with Down syndrome have congenital or acquired thyroid disease. Studies of adults with Down syndrome vary widely, but the incidence of thyroid disease in adults with Down syndrome is believed to be between 13 and 50 percent. Hypothyroidism can occur at any time from infancy through adulthood.

How is hypothyroidism diagnosed?

All individuals with Down syndrome should be tested for hypothyroidism at birth and at periodic intervals (at least every two years) thereafter. The indicators of hypothyroidism -- enlarged tongue, constipation, poor circulation -- are also found in individuals who are not hypothyroid, so the blood test for thyroid function is an important diagnostic test. Because the thyroid hormone affects normal development of the brain, testing of infants is particularly crucial.

What treatment exists for hypothyroidism?

The thyroid hormone, thyroxin, is readily replaced through medication.

What is hyperthyroidism?

In this case, the thyroid gland is overactive. Symptoms are swelling in the neck, abnormal sweating and rapid pulse rate. No evidence exists as to whether hyperthyroidism is more prevalent in individuals with Down syndrome than in the general population.

What is the treatment for hyperthyroidism?

This thyroid malfunction can be treated pharmacologically, blocking the synthesis of thyroid hormone through medication. It can also be treated with radioactive compounds to destroy the gland, or by surgically removing a portion of the thyroid gland.

Are people with Down syndrome more prone to diabetes?

There is not sufficient data available at this point to know if there is increased risk for children with Down syndrome to develop type one diabetes as compared to the rate for their peers in the general population. However, research suggests that individuals who develop one type of endocrine autoimmune disorder, such as thyroiditis, are more likely to develop a second disorder, such as type one diabetes.

What is the status of research on use of the growth hormone for children with Down syndrome?

Use of growth hormone for children with Down syndrome is still in experimental stages. There are reports of increased rates of growth in children with Down syndrome who received the hormone for a brief period; however, these reports were not controlled studies, so there is no scientific evidence that long-term administration of the hormone would increase final height. To date, there is no convincing evidence that head circumference or mental functioning is improved by the use of growth hormone.

Can any growth hormone be administered to any child with Down syndrome?

At present, doctors are licensed to prescribe growth hormone for individuals with Down syndrome only when there is a demonstrated deficiency of that hormone. It is strongly advised that such treatment be obtained only through a clinical trial until long-term benefits are demonstrated.