Gigantism and Acromegaly, What You Should Know

Growth hormone, gigantism, and acromegaly
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Gigantism and acromegaly are two terms that may be foreign to you, but for a 33-year-old woman named Tanya Angus, they are all too familiar. Ms. Angus was diagnosed with acromegaly more than a decade ago, and since that time she has grown from 5 foot 8 inches and 135 pounds to about 7 feet and 400 pounds, according to an ABC News report, and all because of a tumor.

What are gigantism and acromegaly?

Both gigantism and acromegaly are usually caused by the same factor: a benign tumor that has developed on the pituitary gland, causing it to release excessive amounst of growth hormone. When the abnormal hormone production begins during childhood before kids have finished growing, the condition is called gigantism.

In Tanya's case, however, hormone production skyrocketed in her early twenties, after normal bone growth had stopped, and in such cases the disease is called acromegaly.

While a benign tumor on the pituitary gland is the most common cause of gigantism and acromegaly, other causes may include:

  • Carney complex, characterized by an increased risk of developing tumors in the heart and hormone-producing glands
  • Neurofibromatosis, a genetically inherited disorder characterized by the development of tumors that can damage nerves and other tissues
  • McCune-Albright syndrome, a genetic disease caused by mutations of the GNAS1 gene
  • Multiple endocrine neoplasia type 1, a genetic condition caused by a defect in a gene and results in tumor development in various glands

Approximately 20,000 Americans have acromegaly, or about 6 in every 100,000 adults. In addition to excessive height, symptoms include large bones (face, feet, hands, jaw, tongue, and glands in the skin, which leads to excessive sweating and body odor), weakness, fatigue, thickening of the skin, joint pain and swelling, headache, hoarseness, and wide fingers and toes.

The excessive and abnormal growth places undue stress on the body's organs, which can also grow. Therefore, people with acromegaly are at greatly increased risk for a variety of life-altering and life-threatening diseases.

In addition to growth hormone, damage to the pituitary gland can have an impact on the production of other hormones. Therefore, some people with acromegaly also have deficiencies of cortisol (a stress hormone), estradiol (females), testosterone (males), and/or thyroid hormone.

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Fortunately, surgery to remove the tumor is successful in most patients, depending on the tumor's size and location and the skill of the surgeon. Because Tanya's tumor is wrapped around her carotid artery and there are multiple growths, however, the condition is inoperable.

When surgery is not an option or has failed, radiation is an option. However, it can take years for radiation to have any significant impact on growth hormone levels, which means patients will continue to grow. Tanya did not respond to three surgery attempts or radiation.

Medications are available to treat acromegaly, and they can be used before or after surgery, as well as when surgery is off the table. Those drugs include:

  • Octreotide (Sandostatin) and lanreotide (Somatuline Depot) are somatostatin analogs, synthetic types of a growth hormone release-inhibiting hormone called somatostatin. This injectable drug can reduce growth hormone levels by blocking production, and also help shrink tumors. Side effects include diarrhea, intestinal cramps, and gallbladder problems.
  • Pegvisomant (Somavert), a growth hormone receptor antagonist, blocks the effects of growth hormone and can improve symptoms. Given by daily injection, side effects can include diarrhea, fatigue, headache, and nausea.
  • Bromocriptine (Parlodel) and cabergoline (Dostinex), dopamine agonists, which may control the release of growth hormone in some patients, but they are effective for fewer people than are the drugs in the two previous drug classes. Side effects of these oral drugs include headache, intestinal cramps and nausea
  • Estrogen. A new study (August 2012) published in Pituitary reported on the use of estrogen to suppress growth hormone levels in women with acromegaly. The report explains how the addition of estrogen to the treatment of four women who were taking somatostatin receptor ligands or pegvisomant significantly suppressed growth hormone in all the women.

When treatment is delayed or an effective treatment cannot be found, possible complications of acromegaly include arthritis, diabetes, high blood pressure, cardiovascular disease (including stroke, which Tanya has already experienced), hypopituitarism, uterine fibroids, carpal tunnel syndrome, sleep apnea, colonic polyps, and vision problems.

Tanya has been treated with an experimental drug that has finally stopped her growth and brought her growth hormone levels back to normal. Hopefully, these levels will stay low. In the meantime, she has agreed to share some of her experiences with others in a documentary about gigantism and acromegaly.

Chances are, gigantism and acromegaly won't strike you or your family, as these are rare conditions. Little is known about these diseases (the only known risk factor for acromegaly, for example, is a history of pituitary tumor), but experts do know they can affect males and females equally, and that acromegaly most often affects adults in middle age, although Tanya's onset was much earlier.

SOURCES:
ABC News
Mayo Clinic
National Institutes of Health
Shimon I, Barkan A. Estrogen treatment for acromegaly. Pituitary 2012 Aug 30 (Epub ahead of print)

Image: Wikimedia Commons

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Comments

Your otherwise excellent article about acromegaly states, “Fortunately, surgery to remove the tumor is successful in most patients, depending on the tumor's size and location and the skill of the surgeon.” Of course this does rather depend on the definition of “success”. However, it is unfortunately the case that most patients with acromegaly have to wait up to ten years or more to be diagnosed, during which time much damage can occur. Subsequently, around 80% of acromegaly patients are discovered with large tumors of their pituitary, and for them, surgical cure rate, even in the best hands, is only 50% or less. Many patients with acromegaly still have uncontrolled disease and even those in remission suffer ‘quality-of-life’ issues years later. Critically, most people with acromegaly, of which there may be many more thousands than previously realised, remain undiagnosed. Tanya’s case is exceptional, and she has suffered so much as one of the world’s worst and most difficult cases of acromegaly, where doctors have struggled to control her condition, with devastating consequences. For my article about acromegaly specially written for patients, do a Google search for “Jon Danzig guidelines acromegaly”
Thank you for your comments and clarification, and for information on where individuals can get additional information about acromegaly. Hopefully, bringing attention to it will improve public awareness and significantly increase the number of people who are properly and more quickly diagnosed and treated.