As the name suggests, this is a disease in which an individual grows excessively in height to appear ‘giant like’. This occurs due to abnormally excess production of growth hormone (GH) by the pituitary gland (a gland in the brain) during the childhood phase of growth. This is extremely rare with limited data on the incidence of the disease. The tallest reported individual with gigantism is 8 feet 11.1 inches (272 cm).
In adults, excess production of growth hormone does not lead to an increase in height but instead causes coarse facial features, and large extremities called acromegaly.
Cause of Excess Hormone Secretion
- Pituitary adenoma or tumor in the gland
- Hypothalamic release of growth hormone-releasing hormone, which stimulates the production of GH by the pituitary
- Excess secretion of GH from another source
Symptoms of Gigantism
- Sudden rapid growth in height in childhood
- Rapid weight gain and obesity
- Large hands and feet
- Coarse facial features with a projection of the jaw
- Increased sweating
- Amenorrhea in adolescent girls
- Vision disturbance due to a pituitary adenoma
Diagnosis of Gigantism
Early diagnosis is essential to prevent excessive height in adulthood. The diagnosis is suspected from a sudden rapid growth. It is confirmed through the following tests:
- Insulin-like growth factor-I: this rises in response to GH and is used to screen for GH excess
- Growth hormone: this may be elevated, but is not sensitive in picking up excess levels as the GH levels cycle in the body
- GH suppression test: this is the diagnostic test
- Prolactin and Thyroid Stimulation Hormone: these are other hormones produced by the pituitary, and may be raised in case of an adenoma.
- MRI of the brain to look for a pituitary adenoma.
Treatment of Gigantism
There is no way to treat the increased height once growth has been completed. Treatment must be initiated early to ensure normal growth. Multiple treatment options are available:
- Surgery: Surgical removal of a pituitary adenoma is the treatment of choice if this is the underlying cause.
- Radiation of the tumor can be attempted as well
- Medications: these are used if surgery is not adequate or cannot be done
- Octreotide: this can suppress GH release
- Bromocriptine: this was an older drug used to suppress GH release, may be used along with Octreotide
- Pegvisomant: this is a newer drug targeted against the GH receptor.
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- Müssig K, Gallwitz B, Honegger J, Strasburger CJ, Bidlingmaier M, Machicao F, et al. Pegvisomant treatment in gigantism caused by a growth hormone-secreting giant pituitary adenoma. Exp Clin Endocrinol Diabetes. 2007 Mar;115(3):198–202.