Acromegaly

Excess growth hormone

Acromegaly is a hormonal disorder in which there is overproduction of growth hormone. If the disorder begins in puberty, it is called gigantism.

Most cases of acromegaly are caused by a benign (non-cancerous) tumor of the pituitary gland in the brain. The tumor produces excess growth hormone, and as it grows it presses on the brain tissue around it. Most of these tumors occur spontaneously and are not genetically inherited.

In a few cases, acromegaly is caused by a tumor somewhere else in the body, such as in the lungs, pancreas or adrenal glands.

Symptoms

Some tumors grow slowly and produce little growth hormone, so acromegaly is not noticed for several years. Other tumors, especially in younger people, grow quickly and produce a lot of growth hormone. The symptoms of acromegaly come from the growth hormone and from the tumor pressing on brain tissue, and may include:

  • abnormal growth of the hands and feet
  • changes of facial features: protruding brow, lower jaw, and nose; large lips and tongue
  • arthritis
  • headaches
  • difficulty seeing
  • thick, coarse, oily skin
  • snoring or trouble breathing while sleeping (sleep apnea)
  • sweating and skin odor
  • fatigue and weakness
  • enlargement of organs such as liver, spleen, kidneys, heart

Acromegaly may also cause diabetes, high blood pressure, and heart disease.

If the tumor grows in childhood, gigantism results from abnormal bone growth.

The young adult grows extremely tall (in one case, to 8 feet 9 inches tall).

Diagnosis

Testing the level of growth hormone in the blood during an oral glucose tolerance test is a reliable method of confirming a diagnosis of acromegaly. Doctors can measure the blood levels of another hormone, called insulin-like growth factor I (IGF-I), which is controlled by growth hormone.

High levels of IGF-I usually indicate acromegaly. Using computed tomography (CT) or magnetic resonance imaging (MRI) scans of the brain, doctors can look for the pituitary tumor if acromegaly is suspected.

Treatment

Treatment for acromegaly is aimed at:

  • reducing the levels of growth hormone being produced
  • relieving the pressure that the pituitary tumor may be putting on the brain tissue
  • reducing or reversing the symptoms of acromegaly.

The major methods of treatment are:

  • Surgery to remove the pituitary tumor - in most cases, a very effective treatment.
  • Medications to reduce the amount of growth hormone and shrink the tumor - Parlodel (bromocriptine), Sandostatin (octreotide), and Somatuline Depot (lanreotide).
  • Radiation therapy - to shrink tumors that could not be completely removed by surgery.
  • Medication which blocks the effects of growth hormone and reduces IGF-I - Somavert (pegvisomant).

Acromegaly Research

Researchers at Federico II University of Naples in Italy studied 86 individuals with acromegaly who were given medication before and after undergoing partial removal (resection) of their pituitary tumors.

They found that resection of at least 75% of the hormone-secreting tumor enhanced the response to medication. The research was published in the January 2006 issue of Journal of Clinical Endocrinology & Metabolism.

Sources:

Friend, K.E.. "Acromegaly: A new therapy." Cancer Control: Journal of the Moffitt Cancer Center 9(2002).

"Acromegaly." Information on Endocrine and Metabolic Diseases. May 2008. National Institute for Diabetes and Digestive and Kidney Diseases. 7 Jul 2008.

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