Gigantism

Gigantism is characterized by an excess of growth hormone (GH). The excess of growth hormone that brings about gigantism is virtually always caused by pituitary growths (adenomas). As a result of the excessive amounts of growth hormone, children achieve heights that are well above normal ranges. The specific age of onset for gigantism varies between patients and gender, but the common age that excessive growth symptoms start to appear has been found to be around 13 years. Hormonal cause Growth hormone (GH) and insulin-like growth factor-I (IGF-I) are two substances that have been identified as influencing growth plate formation and bone growth and, therefore, gigantism. Their specific mechanisms are still not well understood. More broadly, GH and IGF have both been identified to be involved in most stages of growth: embryonic, prenatal, and postnatal. Moreover, the receptor gene for IGF has been shown to be particularly influential throughout various stages of development, especially prenatally. This is the same for GH receptor genes which have been known to drive overall growth throughout various pathways. Growth hormone is a precursor (upstream) of IGF-I, but each has its independent role in hormonal pathways. Yet both seem to ultimately come together to have a joint effect on growth. Insulin-like growth factor-1 (IGF-1) is an excellent test for evaluation of GH hyper-secretion. It does not undergo diurnal variation and will thus be consistently elevated in GH hyper-secretion and therefore patients with gigantism. A single normal IGF-1 value will reliably exclude GH hypersecretion. ==Genetics==

: its causes, signs and results'' Finding a specific genetic cause for gigantism has proven to be difficult. Gigantism is the primary example of growth hormone hyper-secretion disorders, a group of illnesses that are not yet deeply understood. Additionally, DNA mutations in the aryl hydrocarbon receptor interacting protein (AIP) gene are common in gigantism patients. They have been found to be present in about 29 percent of patients with gigantism. Mutations in AIP, found by sequencing, can have deleterious effects by inducing the development of pituitary adenomas which in turn can cause gigantism. This is typical in gigantism. Additionally, a large variety of other known genetic disorders have been found to influence the development of gigantism such as multiple endocrine neoplasia type 1 and 4, McCune–Albright syndrome, Carney complex, familial isolated pituitary adenoma, X-linked acrogigantism (X-LAG). Although various gene mutations have been associated with gigantism, over 50 percent of cases cannot be linked to genetic causes, showing the complex nature of the disorder. However, in some cases it was observed that the condition had been passed on genetically through a mutated gene. ==Treatment==

Many treatments for gigantism receive criticism and are not accepted as ideal. Various treatments involving surgery and drugs have been used to treat gigantism. Pharmaceuticals Pegvisomant is one pharmaceutical drug which has received attention for being a possible treatment route for gigantism. Reduction of the levels of IGF-I as a result of pegvisomant administration can be effective for the pediatric gigantism patients. Finding the optimal level of pegvisomant is important so normal body growth is not negatively affected. In order to do this, titration of the medication can be used as a way to find the proper administration level. See acromegaly for additional treatment possibilities. ==Terminology==

The term is 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. The term is seldom applied to those who are simply "tall" or "above average" whose heights appear to be the result of normal genetics and nutrition. Gigantism is usually caused by a tumor on the pituitary gland of the brain. Other names somewhat obsolete for this pathology are hypersoma (Greek: hyper over the normal level; soma body) and somatomegaly (Greek; soma body, genitive somatos of the body; megas, gen. megalou great). In the past, while many idividuals were social outcasts because of their height, exceptionally tall people often found work in the entertainment industry, usually either as circus freaks or wrestlers. Additionally, within military history, tall individuals were sometimes specially conscripted, such as in Friedrich Wilhelm I's famous Potsdam Giants regiment. ==See also==