About Acromegaly

Acromegaly is an uncommon hormonal disorder that develops when your pituitary gland produces too much growth hormone during adulthood. When this happens, your bones increase in size, including those of your hands, feet and face. The term “acromegaly” is derived from the Greek words for extremities and enlargement. Acromegaly usually affects middle-aged adults.

In children who are still growing, too much growth hormone can cause a condition called gigantism. These children have exaggerated bone growth and an abnormal increase in height.

Because acromegaly is so uncommon and the physical changes occur so gradually, doctors often don’t recognize it immediately. If not treated promptly, acromegaly can lead to serious illness and even become life-threatening. Treatment of acromegaly involves approaches to lower your production of growth hormone.

Symptoms

One of the most common signs of acromegaly is enlarged hands and feet. People with this disorder often notice that they can no longer put on rings that used to fit, and that their shoe size has progressively increased.

Acromegaly may also cause you to experience gradual changes in the shape of your face, such as a protruding lower jaw and brow, an enlarged nose, thickened lips, and wider spacing between your teeth.

Because acromegaly tends to progress slowly, early signs may not be readily apparent for several years. Sometimes, people notice the condition only by comparing old photographs.

In addition to enlarged hands and feet and facial changes, acromegaly may also produce the following signs and symptoms, which can vary from one person to another:

  • Coarse, oily, thickened skin
  • Excessive sweating and body odor
  • Small outgrowths of skin tissue (skin tags)
  • Fatigue and muscle weakness
  • A deepened, husky voice due to enlarged vocal cords and sinuses
  • Severe snoring due to obstruction of the upper airway
  • Impaired vision
  • Headaches
  • Enlarged tongue
  • Pain and limited joint mobility
  • Menstrual cycle irregularities in women
  • Erectile dysfunction in men
  • Enlarged liver, heart, kidneys, spleen and other organs
  • Increased chest size (barrel chest)

Causes

The pituitary, a small gland located at the base of your brain behind the bridge of your nose, produces a number of hormones. One hormone, called growth hormone (GH), plays an important role in managing your physical growth.

When GH is secreted into your bloodstream, it triggers your liver to produce a hormone called insulin-like growth factor-I (IGF-I). In turn, IGF-I stimulates the growth of bones and other tissues. If your pituitary gland makes too much GH, excessive amounts of IGF-I can result. Too much IGF-I can cause abnormal growth of your soft tissues and skeleton and other signs and symptoms characteristic of acromegaly and gigantism.

In adults, a tumor is the most common cause of too much GH production:

  • Pituitary tumors. Most cases of acromegaly are caused by a noncancerous (benign) tumor (adenoma) of the pituitary gland. The tumor secretes excessive amounts of growth hormone causing many of the signs and symptoms of acromegaly. Some of the symptoms of acromegaly, such as headaches and impaired vision, are due to the tumor mass pressing on nearby brain tissues.
  • Nonpituitary tumors. In a few people with acromegaly, tumors in other parts of the body, such as the lungs, pancreas or adrenal glands, cause the disorder. Sometimes, these tumors actually secrete GH. In other cases, the tumors produce a hormone called growth hormone-releasing hormone (GH-RH), which stimulates the pituitary to make more GH.

Diagnosis

To begin the diagnostic process, your doctor will take a complete medical history and conduct a physical exam. Then he or she may recommend the following steps:

  • GH and IGF-I measurement. After you’ve fasted overnight, your doctor will take a blood sample to measure your levels of GH and IGF-I. Elevated levels of these hormones suggest acromegaly.
  • Growth hormone suppression test. This is the definitive method for verifying acromegaly. In this test, your blood levels of GH are measured before and after you drink a preparation of glucose (sugar). Normally, glucose ingestion depresses levels of GH. If you have acromegaly, your GH level will tend to stay high.
  • Imaging. Your doctor may recommend that you undergo imaging procedures — such as a computerized tomography (CT) scan or magnetic resonance imaging (MRI) scan — to help pinpoint the location and size of a tumor of your pituitary gland. If radiologists, who usually perform the procedures, see no tumor of your pituitary, they may look for nonpituitary tumors that might be responsible for high levels of GH.

Progression of acromegaly can result in major health problems. Complications may include:

  • High blood pressure (hypertension)
  • Cardiovascular disease, particularly enlargement of the heart muscle (cardiomyopathy)
  • Osteoarthritis
  • Diabetes mellitus
  • Precancerous growths (polyps) on the lining of your colon
  • Sleep apnea, a condition in which breathing repeatedly stops and starts during sleep
  • Carpal tunnel syndrome
  • Reduced secretion of other pituitary hormones (hypopituitarism)
  • Uterine fibroids, benign tumors in the uterus
  • Spinal cord compression
  • Vision loss

Early treatment of acromegaly can prevent these complications from developing or becoming worse. If untreated, acromegaly and its complications can lead to premature death.

Treatment

Treatment focuses on lowering your production of GH, as well as reducing the negative effects of the tumor on the pituitary and surrounding tissues. You may need more than one type of treatment.

Surgery
Doctors can remove most pituitary tumors using a method called transsphenoidal surgery. In this procedure, your surgeon works through your nose to extract the pituitary tumor.

Removing the tumor can normalize GH production and eliminate the pressure on the tissues surrounding your pituitary to relieve associated signs and symptoms. In some cases, your surgeon may not be able to remove the entire tumor. This may result in persistently elevated GH levels after surgery, requiring further medical or radiation treatments.

Because of the complex nature of the procedure, it’s important to choose a surgeon experienced in performing this type of surgery. Usually, the more experienced the surgeon, the better the final outcome.

Medications
Drugs used to lower the production or block the action of GH include:

  • Synthetic hormones. The drug octreotide (Sandostatin, Sandostatin LAR)is a synthetic version of the brain hormone somatostatin. It can interfere with the excessive secretion of GH by the pituitary, and thus can produce rapid declines in GH levels. When starting octreotide treatment, you initially inject yourself with a short-acting preparation under your skin (subcutaneously) three times a day to determine if you have any side effects from the medication and if it’s effective. Then, if it’s tolerated and effective, you can take a long-acting form that requires an injection into the muscles of your buttocks (gluteal muscles) by a health care professional, administered once a month.
  • Dopamine agonists. These medications, which include Cabergoline (Dostinex) and bromocriptine (Parlodel),are taken as pills. In some people, they can lower levels of GH and IGF-I. The tumor may decrease in size in some people taking dopamine agonists or octreotide.
  • Growth hormone antagonist. The medication pegvisomant (Somavert), a growth hormone antagonist, acts to block the effect of GH on body tissues. Pegvisomant may be particularly helpful for people who haven’t had good success with other forms of treatment. You administer this medication yourself daily by subcutaneous injection. This medication can normalize IGF-I levels and relieve symptoms in most people with acromegaly, but doesn’t lower GH levels or reduce the tumor size.

Radiation
Your doctor may recommend radiation treatment when tumor cells remain after surgery. Radiation therapy destroys any lingering tumor cells and reduces GH levels. You receive radiation treatment in one of two ways:

  • Conventional fractionated radiation therapy. This type of radiation therapy is usually given daily over a period of four to six weeks.
  • Stereotactic radiosurgery. Also known as gamma-knife radiosurgery, stereotactic radiosurgery can deliver a high dose of radiation to the tumor cells in a single dose while limiting the amount of radiation to the normal surrounding tissues.

The type of radiation therapy that your doctor will recommend depends on the size and location of the remaining tumor cells.

Even after initial treatment, acromegaly requires periodic monitoring by your doctor to make sure that your pituitary is functioning properly. This follow-up care may last for the rest of your life.