Gigantism is caused primarily by an excessive production of growth hormone (GH) during childhood, before the growth plates in the long bones have closed. This overproduction leads to abnormal and rapid growth of bones and tissues, resulting in extraordinary height and size.
The root cause of this excess GH is usually a benign tumor called a pituitary adenoma located on the pituitary gland, which is a small gland at the base of the brain responsible for regulating various hormones including GH. When these tumors develop in children or adolescents whose bones are still growing, they secrete too much growth hormone continuously. This causes the long bones to grow excessively longer than normal, leading to gigantism.
Growth hormone itself plays several roles: it stimulates protein synthesis necessary for tissue growth, affects metabolism by promoting fat breakdown and increasing blood glucose levels, and influences mineral metabolism such as calcium balance important for bone development. When produced in excess during youth, it accelerates skeletal growth dramatically[1][4].
Besides pituitary tumors, other rare factors can contribute to gigantism:
– Genetic mutations affecting genes that regulate GH production or secretion can lead to abnormal hormone levels.
– Damage or injury to parts of the endocrine system involved in hormonal regulation may disrupt feedback mechanisms controlling GH release.
– Certain genetic syndromes may predispose individuals to excessive growth due to altered hormonal pathways[3][6].
If excess GH occurs after bone maturation (after epiphyseal closure), it does not cause increased height but instead results in acromegaly—a condition characterized by enlargement of hands, feet, facial features due to soft tissue and bone thickening rather than lengthening[4].
In summary:
– Gigantism arises from **excessive secretion of growth hormone before bone maturity**.
– The most common cause is **pituitary adenomas producing too much GH**.
– Excess GH stimulates accelerated bone lengthening through increased protein synthesis and mineral metabolism.
– Other causes include genetic mutations or damage disrupting normal endocrine control.
– If excess occurs after puberty when bones stop growing longer but thicken instead—this leads not to gigantism but acromegaly.
This explains why children with untreated pituitary tumors causing high GH can grow extraordinarily tall—sometimes reaching heights well above eight feet—due to unchecked stimulation of their skeletal system during critical developmental years[2][5].
