Acromegaly is a condition of excess growth hormone in adults. Growth hormone (GH) is secreted by the pituitary. In most cases of acromegaly, the overproduction of GH is caused by a benign tumor of the pituitary gland, and treatment most commonly consists of pituitary surgery.
Acromegaly occurs only in adulthood. (In children, excess GH may cause gigantism.) After the growth of childhood is complete, elevated GH levels do not make an individual grow any taller. Instead, the hormone causes overproduction of bone and cartilage, leading to the characteristic symptoms of acromegaly described below.
At the Department of Neurosurgery, our Pituitary Tumor Center helps patients with acromegaly and other pituitary disorders. Our team of nationally and internationally recognized experts includes neurosurgeons, neuroendocrinologists, a radiation oncologist, and a radiologist. Our coordinated approach to pituitary tumor management is unique in the New York metropolitan area.
The symptoms of acromegaly progress so gradually that they often go unnoticed by the patient and by people who see them every day. A friend, relative, or physician who has not seen the patient in some time may be the first to notice the changes, and symptoms tend to exist for years before the disease is diagnosed.
Symptoms vary but may include:
- Enlargement of extremities (may be noticeable as an increase in ring size or shoe size, especially shoe width)
- Prominence of forehead and jaw
- Increasingly wide spacing of teeth
- Thickening of nose, lips, and tongue
- Oily skin
Due to the excess tissue growth caused by the condition, people with acromegaly may also experience carpal tunnel syndrome and other nerve entrapments, radiculopathy, and spinal stenosis.
Other potentially serious complications of acromegaly include diabetes, high blood pressure, sleep apnea, cardiomyopathy, arthritis, colon polyps, and vision loss.
Most symptoms of acromegaly are caused by excessive hormone levels. But some, like headaches and vision loss, may be caused by the mass of the pituitary tumor.
Blood tests can measure the levels of GH and IGF-I. However, levels of GH in the blood can vary minute by minute, and the “normal” range is very large. So even though acromegaly is a condition of elevated GH, a single measurement of GH isn’t very informative. A person with acromegaly could have a “normal” value at the moment of the test, while a person without acromegaly might happen to have a very high level at that moment. IGF-I levels, on the other hand, are fairly stable over the course of a day. An elevated level of IGF-I almost always suggests acromegaly.
A definitive test for acromegaly is the measurement of GH before and after ingesting a glucose preparation. Normally, consuming a lot of sugar temporarily suppresses GH. But in people with acromegaly, GH production continues regardless. GH levels will be nearly as high after the sugary drink as before it. This test is called an oral glucose tolerance test.
Once acromegaly has been diagnosed using one of the methods above, doctors will use an MRI or CT scan to find the tumor. Most tumors are located on the pituitary. If no tumor is found there, other possible tumor sites will be investigated.
Each year, acromegaly is diagnosed in three or four people per million. Most people are diagnosed between 40 and 50 years of age, but symptoms have often been present for 10 years or more at the time of diagnosis.
Acromegaly does not typically run in families. It usually occurs when a single pituitary cell experiences a mutation that causes it to continue growing, dividing, and releasing GH. Over time, the cell grows into a pituitary tumor that releases GH continuously.
Overall, the body’s hormone system is a complex web of interactions, and the production of GH is no different. Normally influenced by food, sleep, stress, and other hormones, GH in turn stimulates body tissue (especially in the liver) to produce an additional hormone: Insulin-like growth factor I (IGF-I). IGF-I is the hormone that directly causes tissue growth—GH is responsible for encouraging the body to produce IGF-I.
In rare cases, a nonpituitary tumor causes acromegaly. The tumor may release GH directly, or it may release another hormone (called GH-RH) that stimulates the pituitary to produce GH. In either situation, the outcome is the same: An elevated GH level leads to an elevated level of IGF-I, and the elevated IGF-I level causes atypical growth.
At the Neurological Institute, our Pituitary Tumor Center team works together to evaluate each patient’s case and form an individualized treatment plan. Our specialists include neurosurgeons, neuroendocrinologists, a radiation oncologist, and a radiologist.
In most cases, neurosurgeons access and remove the pituitary tumor via the nasal passageways. The surgeons pass thin, specialized instruments through the nasal passageways to the back of the sinus and make an opening there. The pituitary gland is located just behind the sinus. The surgeons can then remove as much tumor as is safely possible.
Removing the tumor mass immediately relieves pressure on the surrounding brain structures and prevents future vision loss.
In most patients, GH and IGF-I levels fall rapidly after surgery. Symptoms such as headache, abnormal glucose levels, and sweating improve quickly. As hormone levels normalize over the long term, the thickened tissues in the hands and feet gradually reduce in size. Bone changes, like enlargement of the lower jaw, remain.
The chance of remission after surgery depends on the tumor’s size and location. Patients with remaining tumor after surgery may be treated with medication and/or radiotherapy. These treatments may also be useful for patients who are not good candidates for surgery due to other medical conditions.