Acromegaly is a rare disorder of excessive bone and soft tissue growth due to elevated levels of growth hormone. In young children, prior to the completed fusion and growth of bones, excessive growth hormone can cause a similar condition called gigantism.

Causes

In most cases, acromegaly is caused by over-secretion of growth hormone (GH) produced by a benign tumor of the pituitary gland. The pituitary gland is a small gland located at the base of the brain that produces many hormones. In a small number of cases, malignant tumors of other organs (pancreas, adrenal, lung) may be the source of excess GH.

Risk Factors

A risk factor is something that increases your chances of getting a disease or condition. Some rare cases of acromegaly are hereditary. No other risk factors have been identified.

Symptoms

Symptoms usually develop very slowly over time. Acromegaly can cause serious complications and premature death if not treated.

In children, excess GH production causes elongation of the bones and associated soft tissue swelling. If not treated, children with this disorder can grow to a height of 7-8 feet.

Symptoms and complications in adults may include the following:

• Abnormally large growth and deformity of the:

• • Hands (rings no longer fit)

• • Feet (need a bigger size shoe)

• • Face (protrusion of brow and lower jaw)

• • Jaw (teeth do not line up correctly when the mouth is closed)

• • Lips

• • Tongue

• Carpal tunnel syndrome

• Skin changes, such as:

• • Thickened, oily, and sometimes darkened skin

• • Severe acne

• • Excessive sweating and offensive body order due to enlargement of the sweat glands

• Deepening voice due to enlarged sinuses, vocal cords, and soft tissues of the throat

• Fatigue and weakness in legs and arms

• Sleep apnea

• Arthritis and other joint problems especially in the jaw

• Hypothyroidism

• Enlargement of the liver, kidneys, spleen, heart, and/or other internal organs, which can lead to:

• • Diabetes

• • High blood pressure

• • Cardiovascular disease

• In women:

• • Irregular menstrual cycles

• • Galactorrhea (abnormal production of breast milk) in 50% of cases

• In men:

• • In about 50% of cases, impotence

Diagnosis

The doctor will ask about your symptoms and medical history, and perform a physical exam. The symptoms of acromegaly develop slowly over a number of years. So it is often not diagnosed until years after its onset.

Blood tests will be done to measure the level of insulin-like growth factor (IGF-I), growth hormone releasing hormone (GHRH) , and other pituitary hormones. A glucose tolerance test may also be given to see if the GH level drops—it will not drop in cases of acromegaly. If these tests confirm acromegaly, the following may be done to locate the tumor that is causing the disorder:

• Head CT scan–a type of x-ray that uses a computer to make pictures of the inside of the brain and surrounding structures

• MRI scan–a test that uses magnetic waves to make pictures of the inside of the body, in this case the head

Treatment

The goals of treatment are to:

• Reduce production of GH to normal levels

• Stop and reverse the symptoms caused by over-secretion of GH

• Correct other endocrine abnormalities (thyroid, adrenal, sex organs)

• Reduce the tumor size

Treatment may include:

Surgery–surgical removal of the pituitary tumor, or other tumor, that is believed to be causing acromegaly. In most cases, this is the preferred treatment.

Radiosurgery–the use of highly focused external beams of radiation to shrink the tumor. Used most often in patients who do not respond to conventional surgery or medications.

Radiation Therapy–used in combination with either medical and or surgical treatment

Medication–drugs may be given to reduce the level of GH secretion from the pituitary gland. These include:

• Cabergoline (Dostinex)–given orally

• Pergolide (Permax)–given orally

• Bromocriptine (Parlodel)–may be given before surgery to shrink tumor

• Octreotide (Sandostatin)–given by injections

• Pegvisomant–given by injections for patients not responding to other forms of treatment

Medications must often be combined with other therapies to treat larger tumors affecting surrounding structures.

Prevention

There are no guidelines for preventing acromegaly. Early diagnosis and treatment, however, will help prevent serious complications, some of which are irreversible.

RESOURCES:

American Academy of Family Physicians
http://www.aafp.org

National Institute of Diabetes & Digestive & Kidney Diseases
http://www.niddk.nih.gov

Pituitary Network Association
http://www.pituitary.org

Pituitary Tumor Network Association
http://neurosurgery.mgh.harvard.edu/ptna

References:

Acromegaly Treatment Consensus Workshop Participants. Guidelines for acromegaly management. J Clin Endocrinol Metab. 2002; 87:4054-8

American Academy of Family Physicians website. Available at: http://www.aafp.org.

Cook DM. AACE Acromegaly Guidelines Taskforce. American Association of Clinical Endocrinologists medical guidelines for clinical practice for the diagnosis and treatment of acromegaly. Endoc Pract. 2004; 10:213-25.

Glustina A, Barkan A, Casanueva FF, et al: Criteria for cure of acromegaly: a consensus statement. J Clin Endocrinol Metab. 2000; 85:526-9.

The Merck Manual of Medical Information. Simon and Schuster, Inc.;2000.

National Institute of Diabetes & Digestive & Kidney Diseases website. Available at: http://www.niddk.nih.gov.

Trainer PJ, Drake WM, Katzneison L, et al. Treatment of acromegaly with the growth hormone-receptor antagonist pegvisomant. N Engl J Med. 2000; 342:1171-7.