Too much growth hormone-releasing hormone production may be caused by hypothalamic tumours or by tumours located in other parts of the body (ectopic tumours). The consequence of too much growth hormone-releasing hormone is a rise in growth hormone levels in the bloodstream and, in many cases, enlargement of the pituitary gland.In adults, excessive growth hormone for a long period of time produces a condition known as acromegalyin which patients have swelling of the hands and feet and altered facial features. These patients also have organ enlargement and serious functional disorders such as high blood pressure, diabetes and heart disease. An increase in growth hormone before children reach their final height can lead to excessive growth of long bones, resulting in the child being abnormally tall. This is commonly known as gigantism.However, in most cases, growth hormone overproduction is caused by pituitary tumours that produce growth hormone; only in very rare occasions is excess growth hormone caused by overproduction of growth hormone-releasing hormone.