When pathological GH excess occurs before epiphyseal fusion in the long bone, the condition is known as gigantism.
What causes gigantism and dwarfism among many species arriving on oceanic islands such as the Seychelles?
Overproduction of hGH or IGH-I, or an exaggerated response to these hormones, can lead to gigantism or acromegaly, both of which are characterized by a very large stature.
Gigantism is the result of hGH overproduction in early childhood leading to a skeletal height up to 8 feet (2.5 m) or more.
The somatotropin test also aids in documenting the excess hGH production responsible for gigantism or acromegaly, and confirms underactivity or overproduction of the pituitary gland (hypopituitarism or hyperpituitarism, respectively).
This procedure, also called the glucose loading test, is performed to evaluate excessive baseline levels of hGH and to confirm diagnosis of gigantism in children (and acromegaly in adults).
In a child with excessive hGH levels, failure of suppression indicates anterior pituitary dysfunction and confirms a diagnosis of gigantism (or acromegaly).
If such a tumor develops within the first ten years of life, the result is gigantism (in which growth is accelerated) and not acromegaly.
If the tumor develops after growth has stopped, the result is acromegaly, not gigantism.
In adults, this condition results in an enlargement of bones; in children, the abnormality results in excessive height and is called gigantism.
This variant is called gigantism, with the additional bone growth causing unusual height.
Gigantism occurs even more rarely, with reported cases in the United States numbering only about 100 by 2004.
Onset of gigantism is usually at puberty, although some cases of toddlers and young children with gigantism have been reported.
The most common cause of acromegaly and gigantism is the development of a noncancerous tumor within the pituitary, called a pituitary adenoma.
Children and adolescents with gigantism show a characteristic lengthening and enlargement of bones, principally of the limbs.
By contrast, the effects of gigantism are typically dramatic, with remarkable changes over a short period of time.
Individuals with acromegaly or gigantism who have diabetes or diabetes-like symptoms should maintain a diet that helps normalize blood sugar levels.
The initial onset of acromegaly or gigantism cannot as of 2004 be prevented.
In individuals with gigantism who are not treated, linear growth can continue unchecked for several decades.
"Gigantism and Acromegaly." eMedicine, July 29, 2004.
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