Growth hormone is produced in the pituitary gland--a hormone-producing organ located in the brain. It stimulates growth of the long bones in the body as well as growth of some organs. When levels of this hormone are higher or lower than normal, the abnormality affects children and adults differently with respect to physical growth.
High Levels
Gigantism and acromegaly are hormonal diseases that occur when the pituitary gland secretes too much growth hormone. Gigantism only affects children whose growth plates have not yet closed. The Merck Manuals Online Medical Library reports that children affected by this disorder grow very tall.
Excess growth hormone in adults causes acromegaly. In acromegaly, the bones grow thicker, not longer. Symptoms of this condition are thicker ribs which lead to a barrel chest, deeper voice, a protruding jaw and swollen hands and feet.
Low Levels
A lack of growth hormone in the body affects children and adults differently. In children, this problem leads to impaired growth as manifested by short stature or height. The effects of low growth hormone in adults are not based on height. Instead, low growth hormones in adults cause a reduction in muscle tissue, an increase in fat tissue, thinner bones and a decrease in energy.
Causes
Overproduction or underproduction of growth hormone may be caused by tumors in the pituitary gland, inflammatory diseases or inadequate blood supply to the pituitary glands.
Diagnosis
If a growth hormone disorder is suspected, a doctor can measure growth hormone levels in the blood. Unfortunately, measuring growth hormone levels on one occasion only is unreliable. Growth hormone is secreted in bursts, so its presence in the blood fluctuates under normal circumstances.
To get a more accurate measurement of growth hormone in the body, a glucose drink is given to a patient. After this, the patient's blood is tested for growth hormone. Normally, the drink should suppress growth hormone levels in the body. If growth hormone is being overproduced, its level in the body will not be suppressed.
Measurement of insulin-like growth factor 1 or IGF-1 in the blood can also help determine abnormalities in growth hormone levels.
The National Endocrine and Metabolic Diseases Information Service explains that after blood tests are done to verify an imbalance in growth hormone, imaging technology such as magnetic resonance imaging is used to visualize the pituitary gland. If abnormal growth hormone levels are caused by pituitary tumors, imaging technology helps the physician to detect the size and location of the tumors.
Treatment
Children who lack growth hormones are given synthetic hormones through injections. This helps them grow at a healthier rate. In adults with growth hormone deficiency, growth hormone injections make the bones thicker.
Excess secretion of growth hormone caused by pituitary tumors may be treated by surgical removal of the tumors or radiation therapy to kill off the cancer cells. Drugs like bromocriptine are used to block production and secretion of growth hormone.
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