Excessive growth, resulting from heredity, diet, or growth regulation disorder. Androgen deficiency causes long bones to continue growing after they would normally stop. Overproduction of growth hormone—usually due to a tumour—causes pituitary gigantism (see pituitary gland). With gradual but continuous growth, height may reach 8 ft (240 cm), with normal proportions. Greater susceptibility to infection, injury, and metabolic disorders shortens the life span. Surgery or radiation can be employed to curtail further growth. Gigantism often occurs with acromegaly.
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The term has been typically applied to those whose height is not just in the upper 1% of the population but several standard deviations above mean for persons of the same sex, age, and ethnic ancestry. Typical adult heights of Americans of European descent to whom the term might be applied are 2.10 - 2.40 metres (7 - 8 feet). The term is seldom applied to those who are simply "tall" or "above average" - whose heights appear to be the healthy result of normal genetics and nutrition.
Other names somewhat obsolete for this pathology are hypersomia (Greek: hyper over the normal level; soma body) and somatomegaly (Greek; soma body, object pronoun somatos of the body; megas, megalos great).