Growth hormone is a type of protein produced by pituitary gland situated in the brain, which then circulates in the blood. It’s main biological role is to promote growth of bone and tissues in children until the completion of puberty. Production declines in middle age. Some amount of it is also produced by intestine and pancreas.
In normal circumstances, the level of growth hormone rises at night, during physical activity and stress. However, in some diseases growth hormone may abnormally increase. This may lead to conditions such as gigantism in prepuberty children and acromegaly in adults.
Causes Of Increased Growth Hormone
There are several disorders that can cause excess secretion of human growth hormone. As mentioned earlier, physical activity, stress and sleep are the potent stimuli, but they do not cause any deleterious effect on the body as the release is in pulsatile fashion. However, certain conditions such as pituitary tumor, genetic diseases can cause its abnormal rise for a long and sustained period of time. These conditions are as follows:
- Pituitary gland tumor: A tumor of pituitary gland is the most common cause of excess secretion of growth hormone. In majority of cases it is a benign adenoma. These adenomas are made up of cells called somatotroph. The adenomas grow very slowly over years accelerating the production of GH. Eventually they enlarge too much in size and compress the adjacent tissues in the brain leading to headache, and impaired vision.
- Tumors in other organs: Tumors other than pituitary tumor can also cause increased secretion of growth hormone. Tumors in lungs, pancreas, hypothalamus or adrenal glands may secrete more amount of a hormone called growth hormone-releasing hormone GH-RH. This hormone may stimulate the pituitary gland for an increased secretion of GH.
- Genetic conditions: A genetic disorder called multiple endocrine neoplasia type 1 is known to cause increase of growth hormone in blood. The condition causes growth of tumors in many endocrine glands. If the tumor grows in pituitary gland which has cells that secrete GH, it may cause increased production of growth hormone. Another genetic disorder called Mccune-albright syndrome can also cause this condition.
Symptoms Of Increased Growth Hormone
Increased level of growth hormone for a prolonged period of time can lead to conditions such as gigantism in prepuberty period and acromegaly in adults. Patients with gigantism have abnormal tall stature. In acromegaly the bones of jaw, fingers and toes become thick. The face is disfigured due to abnormal nose, prominent supra orbital ridge, thick lips and hair on lips in females.
Patient may have difficulty in biting due to large jaw size. Thick voice, skin tags, increased sweating, high blood pressure, pressure on nerves leading to pain, weakness of muscles, increased extension of joints, reduced sexual desires and function are some of the manifestations of acromegaly.
Some patients may suffer from diabetes. The skin becomes thick with prominent creases of palm. Enlarged pituitary tumor can cause headache, and vision problems.
Treatment For Excess Growth Hormone
The diagnosis of increased growth hormone level can be made from characteristic clinical appearance. However, blood tests for GH are also useful for diagnosis. CT and MRI imaging are also useful for tumor localization.
Increased growth hormone level causes gigantism and acromegaly. The main aim of treatment is to normalize growth hormone level. Surgical removal of pituitary mass normalizes growth GH. Growth hormone secreting adenomas are also treated with medications and radiation therapy when surgery is not possible.