Regulating growth hormone (GH) is a normal function of the pituitary gland. GH controls the development of the body’s bones and organs, a significant role in childhood. Adults still need GH, but less so than children and when the pituitary gland produces too much growth hormone in adults, it causes bones and organs to become too large. This rare condition is called acromegaly. Changes to the body may take place slowly over many years. Though acromegaly can begin any time after puberty, it affects mostly middle-aged adults. Untreated, the disease can lead to many complications, severe illness and/or early death due to cardiovascular disease.
At the OHSU Pituitary Center, we take care of a large number (about 200) of patients with acromegaly, a very high volume for a rare disease. The director of the OHSU Pituitary Center, Maria Fleseriu, M.D., F.A.C.E., is a leading international expert who specializes in acromegaly and Cushing’s disease.
Acromegaly is a rare disease. There aren’t exact data, but scientists estimate that fewer than 100 people per million develop acromegaly, but several recent studies suggest that acromegaly may affect as many as 1,000 people per million. Both men and women can develop acromegaly, in roughly equal numbers. Because it develops slowly, many people are not diagnosed until they are in their 40s and 50s, with a mean delay in diagnosis of about 10 years.
In almost all cases, acromegaly is caused by a benign tumor affecting the pituitary gland. This tumor is called an adenoma. Most adenomas are not inherited and occur spontaneously.
Acromegaly can take several decades to develop because pituitary adenomas (noncancerous tumors) that make too much growth hormone usually grow slowly. Some people with acromegaly notice their ring size or shoe size getting larger over 10 or 15 years. Changes can happen so slowly that doctors often don’t diagnose acromegaly until it has been present for a long time. Often, patients’ first awareness of GH-secreting pituitary adenomas comes when they have headaches or vision problems.
- Hands and feet getting larger
- Jaw and forehead getting larger
Acromegaly can also cause:
- Arthritic (painful, swollen) joints and back pain
- Thickened skin and skin tags
- Oily skin, sweating more than usual
- Deep and “throaty” voice
If you have acromegaly, you might develop another medical condition, such as:
- Carpal tunnel syndrome
- High blood pressure and vascular disease
- Heart disease
You might not know you have acromegaly for many years because it develops so slowly. Plus, the symptoms of acromegaly can be similar to other medical conditions. To diagnose acromegaly, you might have the following tests:
- Growth hormone (GH) and insulin growth factor-1 (IGF-1) measurement
You will give a blood sample to assess both GH and IGF-1 levels. Although high levels of these hormones suggest acromegaly, GH levels may be in the normal range in mild or early disease because GH levels naturally rise and fall throughout the day. If IGF-1 is elevated, you will need further evaluation.
- GH suppression test
For a clear diagnosis, we might use a GH suppression test. This requires fasting overnight and multiple blood draws over a period of two hours. For your comfort and to collect samples at regular intervals, we will place an IV in your arm before the first blood draw. First, we will check the levels of GH, IGF-1 and glucose (sugar) in your blood for a baseline. Then you will be given a preparation of glucose to drink. Glucose lowers levels of GH. If GH remains high or above a specific cut-off level, the test confirms too much GH is produced, leading to a diagnosis of acromegaly.
Your referring provider may have previously ordered an MRI to determine if you have a pituitary tumor. This imaging can show the size and location of any mass in your pituitary. It can also help doctors determine if a pituitary tumor is affecting or will affect your eyesight. If there are adequate views of the pituitary from the first scan, we will not repeat the MRI.
- Other tests
After our providers have reviewed the data, you may be asked to undergo more specific testing. For example, our neuro-ophthalmologist may evaluate your vision or our neurosurgeon may perform an exam. We might also order additional testing to evaluate comorbidities.
For most patients with acromegaly, surgery is the initial treatment to remove the pituitary adenoma (noncancerous tumor) that is making too much growth hormone (GH). These tumors are usually larger than 1 cm (about the size of a small grape) by the time they are visible on MRI. Larger tumors pressing on the pituitary gland or optic nerve can affect vision and other functions.
Most pituitary tumors are removed through the nose, in a procedure called transsphenoidal surgery. This approach leaves no obvious scars and has fewer side effects and risks. Patients often go home the day after surgery.
Removing the tumor can reduce GH secretion and if GH normalizes, stop the progress of acromegaly.
For some people, surgery is not an option or doesn’t fully control acromegaly.
We recommend medication:
- For people who can’t have surgery due to other health reasons or risks.
- For people who have surgery, but the neurosurgeon couldn’t remove the whole tumor due to size and location.
- For people who have too much GH, but a tumor doesn’t show on imaging.
For these patients, medication is the next course of action. Some of the medications that reduce GH for treating acromegaly have been in use for decades and have worked successfully for about half the patients who use it. Other people may need a combination of medications to control GH.
There are two classes of medication for control of GH:
- Central-acting inhibitors of GH secretion
Doctors have used these types of medications (abbreviated to SRLs for somatostatin receptor ligands) for a long time to treat acromegaly. In about 50–60 percent of patients, these SRLs can normalize GH and insulin-like growth factor 1 (IGF-1). The remaining 40–50 percent of patients may have improvement, but need a combination of other medications to bring GH into a normal range. For example, a medicine called cabergoline (a dopamine agonist), not FDA approved for acromegaly but approved for prolactinomas, can be used in combination with an SRL.
- GH receptor-blocking agents
Pegvisomant (Somavert) is a medication that takes a different strategy to reduce GH. Patients may need varying doses of this medicine to get GH to normal levels. About 60 percent of patients can take a low dose (20 mg) and get results, but others may need a higher dose (40 mg). At the higher dose, up to 90 percent of patients control GH and IGF-1 levels. For patients who need a combination therapy, pegvisomant can be used with an SRL.
SRLs and pegvisomant are given by injection — intramuscular or deep subcutaneous for SRLs and subcutaneous for pegvisomant. Depending on the medication, you may take it daily, weekly or monthly. You may be able to give yourself the shot or you may need to visit your health care professional to receive it. There are side effect risks with all medications. Many are mild, but depending on the combination of medications, you may need to be closely monitored by your doctor.
Some people have an aggressive form of acromegaly that may not respond to surgery and medication. In these cases, we may recommend radiation. One method is through stereotactic radiosurgery, which uses precisely targeted radiation to reach any leftover or otherwise unreachable portions of the original tumor. Patients will require medication until radiation is able to control the GH secretion, and this might take up to 10 years. Your doctor will talk with you about the best treatment option for you.
Acromegaly symptoms can be subtle and slow. Often, your future health is related to how far acromegaly progressed before you were diagnosed. If it is discovered in the early stages, outcomes are usually positive.
If treated at a center with staff who have specialized training, expertise and advance imaging techniques, surgery to remove pituitary tumors is usually successful. After surgery, if GH levels return to normal naturally or with the help of medication, a person with acromegaly has the same risk of death as the general population.
However, having your hormones out of balance can cause serious medical conditions. Your risk of additional medical conditions may be higher than normal, even after treatment, due to high GH for a prolonged period.
Your doctor may examine and test you for:
- Cardio- and cerebrovascular problems (heart attack, stroke and other problems)
- Colon polyps (benign growths)
- Sleep apnea (stopping breathing during sleep)
- Carpal tunnel syndrome (wrist pain, numb fingers)
Your doctor will talk with you to decide on a care plan if you have any of these conditions.
Clinical trials are the final step in a long process of research. These studies allow scientists to test the value of their research to diagnose, treat and prevent diseases and disabilities. Each clinical trial is an opportunity to test a promising invention or treatment.
The OHSU Pituitary Center is a national leader in research related to pituitary conditions. Our scientists were major contributors to clinical studies that resulted in two new, FDA-approved, ﬁrst-in-their-class treatments for Cushing’s disease and one for acromegaly.