Does your child seem much shorter - or much taller - than other kids his or her age? It could be normal, or it could be a sign of a problem. Very slow or very fast growth can sometimes signal a gland problem or disease.

The pituitary gland makes growth hormone, which stimulates the growth of bone and other tissues. Children who have too little of it may be very short. Treatment with growth hormone can stimulate growth.

People can also have too much growth hormone. Usually the cause is a pituitary gland tumor, which is not cancer. Too much growth hormone can cause gigantism in children, where their bones and their body grow too much. In adults, it can cause acromegaly, which makes the hands, feet and face larger than normal. Possible treatments include surgery to remove the tumor, medicines and radiation therapy.

One of the remarkable roles of the endocrine system is the regulation of growth and development throughout our bodies. This work is directed by the pituitary gland - perhaps the most important "master gland" of the endocrine system. A small oval-shaped organ at the base of the brain, the pituitary gland releases a variety of hormones into the blood stream. One of these is growth hormone (GH) called somatotropin. Once in the blood, GH travels to bone, muscle, and other tissues where it has many effects. The hypothalamus, a small structure located at the base of the brain just above the pituitary, controls the release of growth hormone by the pituitary gland. The principal stimulator of growth hormone secretion is called the growth hormone-releasing hormone.

In children, for example, GH stimulates linear growth, or height. It is also important for the development of muscle and bone, and the distribution of body fat throughout the body. In adults, GH affects energy, muscle strength, bone health, and psychological well being. Having either too much or too little GH can cause health problems.

In some cases, individuals may have too much GH, a condition called acromegaly in adults. Acromegaly is usually caused by a non-cancerous tumor of the pituitary gland. In the rare instances when it occurs, too much GH in children causes gigantism.

A more common growth disorder is growth hormone deficiency (GHD). This is the condition of having too little GH. There are several possible explanations for its occurrence:

• A child can be born with GHD.
• The condition also may arise because of damage to the hypothalamus or pituitary gland as a child or adult because of a tumor, an infection, or radiation to the brain - usually for the treatment of a tumor.
• A deficiency in GH may also have an undefined cause. (In this case, it is said to be of idiopathic origin.)

Pituitary disorders, such as GH excess or GHD, are evaluated and treated by endocrinologists - medical specialists in hormone-related conditions. Because the diagnosis and treatment of such disorders require special expertise, primary care physicians who suspect patients have GH abnormalities should refer them to an endocrinologist.