Thousands of Diseases Afflicting Humans

¶ … thousands of diseases afflicting humans throughout the world. It is important to look at gigantism and determine its causes, symptoms, the population likely to suffer from the disease and any prevention or treatments that are available.

What is Gigantism

Gigantism is a disease which results in a person having "extraordinary physical proportions (http://jcem.endojournals.org/cgi/content/full/84/12/4379)." There have been reports throughout history of individuals exhibiting these qualities, and the "concept of superhuman size, whether in the form of Goliath, Hercules, of Bigfoot, has consistently inspired a sense of awe and enthrallment (http://jcem.endojournals.org/cgi/content/full/84/12/4379)."

Causes of Gigantism

Gigantism is caused by an excessive amount growth hormone (GH) being secreted by the pituitary (Simmons, 1999). This excess of GH occurs "during childhood when open epiphyseal growth plates allow for excessive linear growth (http://jcem.endojournals.org/cgi/content/full/84/12/4379)."

Almost every case of gigantism is caused by a "benign tumor of the pituitary gland, known as a growth-hormone-producing pituitary adenoma (www.mayoclinic.com)."

It can be "caused by eosinophilia or chromophobe adenoma and its usual course is insidious (www.medfamily.org/diagnosis/P/diagnosis-terms-Pituitary_gigantism)." Other causes include:

somatotropic cell adenoma of the pituitary somatotropic cell adenoma of mixed cell somatotropic cell adenoma of stem cell bronchial adenoma pancreatic islet cell tumor carcinoid tumor ectopic growth hormone production (www.medfamily.org/diagnosis/P/diagnosis-terms-Pituitary_gigantism)."

Symptoms

Gigantism is characterized by "craniofacial overgrowth, with the mandible being more affected than the maxilla (Simmons, 1999)." person may experience headaches, loss of vision or other problems with the central nervous system if there is a large pituitary tumor.

Gigantism can also exhibit the following "signs and symptoms:

Abnormally tall stature

Disproportionately large hands, feet and facial bones

Enlargement of the heart

Degenerative arthritis

Excessive sweating

Snoring and sleep apnea

High blood pressure

Diabetes (www.mayoclinic.com)." doctor may suspect gigantism if there is "inappropriate excessive growth spurt, dorsal kyphosis, manifestations of generalized osteoporosis, thickening of skin and soft tissue growth (www.thedoctorslounge.net/clinlounge/diseases/endocrinology/gigantism)."

Diagnosis

If a physician suspects an individual has gigantism, tests are run which include:

Glucose tolerance test: Normally growth hormone is suppressed after oral intake of 50mg of glucose due to inhibition of GHRH secretion. In cases of gigantism, growth hormone levels fail to suppress or may even rise.

Insulin-like growth factor-1 (IGF-1, somatomedin C) assays: are always elevated in gigantism and do not fluctuate like growth hormone levels (www.thedoctorslounge.net/clinlounge/diseases/endocrinology/gigantism)."

Treatments

Treatments of a "pituitary tumor may include radiation therapy, medications to decrease growth hormone production or block its action, or surgery to remove the tumor. Surgery can cure the disease if the entire tumor can be removed. The chances of cure are much higher when the tumor is small and has not spread beyond the pituitary gland (www.mayoclinic.com)."

Surgical options include "tranfenoidal adenectomy or hypophysectomy of the acidophil adenoma. Drugs used to reduce growth hormone levels include bromocriptine and cabergonline, which is another dopaminergic agent. External radiotherapy is an option in treating acidophil adenomas (www.thedoctorslounge.net/clinlounge/diseases/endocrinology/gigantism)."

In 2002, it was announced that a new group of proteins, which were discovered in 1997 by Australian researchers, may offer hope to sufferers of gigantism.

This protein group is known as "SOCS - or suppressors of cytokine signaling. The SOCS act as 'negative regulators' that suppress the hormones responsible for cell growth. Since then, research has shown the regulating the activity of SOCS could 'turn on' or 'turn off' the hormones that influence obesity, gigantism or dwarfism, was well as strengthening the body's immune response to disease (Skatssoon, 2002)." The research is currently being conducted by the Cooperative Research Centre for Cellular Growth (CRC-CGF), and researchers there are optimistic that they will be able to turn the over stimulated cell off with drugs once they know how these proteins work.

By discovering that an individual's "SOCS gene was not functioning, doctors could help those who are clinically large due to the excess GH and turn off the protein (Skatssoon)." While clinical trails are currently only being conducted on mice, the goal is to begin human trials by 2007.

In Japan, the health authority recently approved the use of "Sandostatin LAR (octreotide acetate for injectable suspension) for the treatment of pituitary gigantism which is unresponsive to or unsuitable for surgery or other drug therapies (unknown, 2004)." This drug has already won approval for use in Europe and the United States. Studies conducted show that the drug "targets the tumor to control in four areas: in the site where hypersecretion starts, in GH secretion, IGF-1 and in the symptoms associated with the disease (Unknown, 2004)." While the drug has been approved, there are still contraindications to taking it such as a patient who has an irregular or slow heart rate, or blood sugar levels which are either too high or too low.

Occurrence

Although gigantism begins prior to puberty, the "majority of giants eventually demonstrate features of acromegaly, of which the mean age for the onset is within the 3rd decade of life. Even a congenital onset of GH excess has been suggested by linear growth acceleration occurring within the first few months of life in young children with documented gigantism (http://jcem.endojournals.org/cgi/content/full/84/12/4379)." Although there is no accurate number of individuals who have had gigantism, the disease is so rare that there have only been around 100 reported cases.

Prognosis and Complications

There is no prevention for gigantism, however the patient can expect a good prognosis from pituitary surgery due to its ability to limit GH production.

An individual may develop complications such as "the development of secondary sexual characteristics may be delayed, and surgery and radiation can both lead to deficiencies in other pituitary hormones causing hypothyroidism, adrenal insufficiency, hypogonagism, and in rare cases diabetes insipidus (www.shands.org/health/information/001174trt.htm)."

Gigantism usually "occurs as an isolated disorder, however it may also be a feature of an underlying medical condition such as multiple endocrine neoplasia (MEN) type-1, McCune-Albright syndrome (MAS), neurofibromatosis, Carney complex (http://jcem.endojournals.org/cgi/content/full/84/12/4379)."

Conclusion

Gigantism is a disease that affects an individual prior to puberty, unlike the similar disease acromegaly, which strikes later in life. The condition is caused by excessive growth hormone secretion. This hormone "stimulates the growth of bones, muscles, and many internal organs and excessive amounts lead to abnormally robust growth of all of these tissues. Certain rare tumors of the pancreas and lungs also can produce hormones that stimulate the pituitary to produce excessive amounts of growth hormone (http://www.merck.com/mmhe/sec13/ch162/ch162e.html)."