Overproduction of growth hormone causes excessive growth. In children, the condition is called gigantism. In adults, it is called acromegaly.
- Excessive growth hormone is almost always caused by a noncancerous (benign) pituitary tumor.
- Children develop great stature, and adults develop deformed bones but do not grow taller.
- Heart failure, weakness, and vision problems are common.
- The diagnosis is based on blood tests and imaging of the skull and hands.
- Computed tomography (CT) or magnetic resonance imaging (MRI) of the head are done to look for the cause.
- A combination of surgery, radiation therapy, and drug therapy is used to treat the overproduction of growth hormone.
Growth hormone is produced by the anterior lobe of the pituitary gland. Growth hormone stimulates the growth of bones, muscles, and many internal organs. Excessive growth hormone, therefore, leads to abnormally robust growth of all of these tissues. Overproduction of growth hormone is almost always caused by a noncancerous (benign) pituitary tumor (adenoma). Certain rare tumors of the pancreas and lungs also can produce hormones that stimulate the pituitary to produce excessive amounts of growth hormone, with similar consequences.
Treatment
- Surgery
- Radiation therapy
- Drug therapy
Surgery
Surgery to remove the pituitary tumor by an experienced surgeon is currently regarded as the best first treatment for most people with acromegaly caused by a tumor. It results in an immediate reduction in tumor size and growth hormone production, most often without causing deficiency of other pituitary hormones.
Unfortunately, tumors are often large by the time they are found, and surgery alone does not usually cure the disorder. Radiation therapy is often used as a follow-up treatment, particularly if a substantial amount of the tumor remains after surgery and acromegaly persists.
Radiation therapy
Radiation therapy involves the use of supervoltage irradiation, which is less traumatic than surgery. This treatment may take several years to have its full effect, however, and often results in later deficiencies of other pituitary hormones, as normal tissue is often also affected. More directed radiation therapy, such as stereotactic radiosurgery, is being tried to speed results and spare the normal pituitary tissue.
Drugs
Drug therapy can also be used to lower growth hormone levels. The most effective drugs are those that are forms of somatostatin, the hormone that normally blocks growth hormone production and secretion. These drugs include octreotide and newer long-acting related drugs, which only have to be given about once a month. These drugs are effective in controlling acromegaly in many people as long as they continue to be taken (they do not provide a cure). Their use has been limited by the need to inject them and by their high cost. This may change as such drugs become longer acting and more readily available.
Occasionally, bromocriptine and other related drugs are of some benefit but are not as effective as octreotide. Several new growth hormone blocker drugs, such as pegvisomant, are now available and may be useful for people who do not respond to somatostatin-type drugs.