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Growth Hormones

Abnormal Growth

A number of hormonal conditions can lead to excessive or diminished growth. Because of its critical role in producing hGH and other hormones, an aberrant pituitary will often yield altered growth. Dwarfism (very small stature) can be due to lack or under-production of hGH, lack of IGH-I, abnormalities in GH receptor or other changes leading to irresponsiveness of the target tissues to GH. Overproduction of hGH or IGH-I or an exaggerated response to these hormones can lead to giagantism or acromegaly both characterized by a very large stature.

Short stature can result not only from total absence of hGH, but also from GH deficiency. Children deficient in hGH have normal size at birth, but their postnatal growth is decreased leading to short stature, delayed bone maturation and delayed puberty. In contrast, absence of hGH can cause smaller birth lengths.

Giagantism is the result of hGH overproduction in early childhood leading to a skeletal height up to 8 ft (2.5 m) or more. Another condition, called acromegaly results from overproduction of hGH in adulthood. In this condition, the epiphyseal plates of the long bones of the body do not close, and they remain responsive to additional stimulated growth by hGH leading to increased bone thickness and length. People diagnosed with acromegaly develop increasingly enlarged and exaggerated facial bones. Also, acromegalic patients have pronounced, enlarged joints such as in the hands, feet, and spine.

Simple variation in height are due, in part, to a range of hGH levels due to factors already mentioned. However, parents concerned about their child's growth should discuss this with a pediatrician. hGH levels can be evaluated, and hormone therapy using synthetic hGH is a possibility. The hGH that is therapeutically used is now produced using genetic engineering. Recombinant human growth hormone (rhGH) is a protein produced from genetically altered cells. General growth patterns vary normally, however, and bone age is actually a more accurate reflection of regular development than age itself. Some children can be as much as a year off of average development. These children's growth rates may catch up or slow down compared to their peers. Growth patterns often follow family trends, such that if a boy's father was relatively small until puberty, during which time he outgrew his peers, then the boy may repeat this path. Some debate exists over the use of genetically engineered hGH to treat small stature. Some have debated that using hGH simply to make people taller is unethical and an example of science tampering with processes best left untouched.

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Science EncyclopediaScience & Philosophy: Glucagon to HabitatGrowth Hormones - Normal Growth, Abnormal Growth, Aging And Growth Hormone Therapy In Adults