Growth hormone does what it says
The pituitary gland is responsible for producing many different hormones. Some of these hormones act directly on parts of the body, while some trigger other glands to release their own hormones
One hormone produced by the pituitary gland that acts directly is called growth hormone (GH) and it doesn't take a genius to figure out what it does. Growth hormone stimulates the growth of muscle, cartilage and bone.
Overproduction of growth hormone
In rare circumstances, the pituitary gland may produce excessive amounts of GH. Invariably this is the result of the presence of a pituitary tumour, which in most cases is non-cancerous. Occasionally these tumours appear as part of an inherited condition called multiple endocrine neoplasia, in which tumours develop in several different hormone-producing glands around the body.
However, why these tumours in the pituitary gland occur in the first place remains a mystery. Since the pituitary gland is located just below the brain, as it grows it may press on the brain, causing headaches. It may also affect vision, which is usually noticed as a reduction in a person's field of vision.
Rampant growth
When excessive growth hormone is present before puberty it causes rampant growth, or gigantism
When excessive growth hormone is present before puberty it causes rampant growth, or gigantism. It's more common, however, for pituitary tumours to occur in adulthood. Although in adulthood the long bones of the arms and the legs are no longer capable of growing, the bones of the hands, feet, and face can still grow, and do so.
This enlargement, which takes place over years, may only be noticed when old photographs are compared with recent ones or when larger shoes are needed.
Characteristics
This condition that results from excessive production of GH is called acromegaly. The hands become spade-like in appearance as they get bigger. Growth of the facial bones causes the face to change shape too. The jaw becomes larger, with spaces appearing between the teeth, and the eyebrows become more prominent. The tongue enlarges and the skin becomes coarse and oily.
Non-bony parts of the body (soft tissue) may also grow larger, which leads to weight gain and thickening of the skin. Other characteristic changes that occur in acromegaly include deepening of the voice, excess sweating and numbness and tingling in the hands and feet.
Acromegaly can have more serious effects on the body. If it's not treated then diabetes mellitus and chronic heart failure may occur.
Overcoming the problem
Once the diagnosis has been confirmed with blood tests and scans, treatment can be provided. This may include a combination of surgery to remove the tumour, radiotherapy to destroy any tumour cells, and drugs to suppress the production of GH.
Regular follow-up monitoring is provided and in time, although the bones will remain the same size, any soft tissues that have enlarged will become smaller. For further information, please visit The Pituitary Foundation website.
This article was last medically reviewed by Dr Rob Hicks in December 2005.
