What You Should Know About Acromegaly

By C. Rachel Kilpatrick, MD and Julie M. Silverstein, MD

What is acromegaly?

Acromegaly [ak-row-meg-a-le] is a disorder characterized by overproduction of growth hormone and is most commonly caused by a benign tumor of the pituitary gland that secretes excess growth hormone. Growth hormone is one of seven different hormones made by cells within the pituitary, a pea-sized gland which lies in a small bony pocket between the sinuses of the face and the base of the brain. Normally, growth hormone is partially responsible for maintaining adequate growth in children. Excess growth hormone in children, however, causes abnormally rapid growth which results in gigantism [ji-gan-tizm], a condition characterized by excessive growth and height significantly above average. In adults, because growth in one’s height has stopped, excess growth hormone causes acromegaly, with overgrowth of small bones such as in the hands, in soft tissues and organs, such as the heart.

I seem to be getting bigger

Fortunately, acromegaly is uncommon and affects only about one person in 300,000. However, because the signs and symptoms of acromegaly develop slowly over time and may be subtle, there can be a delay in making the diagnosis. Most of the symptoms of acromegaly are due to the effects of excessive amounts of growth hormone on the body. The physical findings can include the growth of skin tags, thickening of the skin, excessive sweating, and enlargement of the hands and feet, which might cause an increase in ring or shoe size, certainly something that could be normal with aging. Other findings can include an enlarged forehead, nose and jaw and an increase in the space between the bottom teeth due to growth of the facial bones. Sometimes it is helpful to compare the face to an old photograph to see these changes.

Acromegaly also may cause soft tissue swelling which, when present in the hands, can cause carpal tunnel syndrome, pinching of the median nerve at the wrist, or neuropathy (nerve irritation). Soft tissue swelling in the back of the throat can cause snoring and sleep apnea, leading to disturbed sleep and daytime sleepiness. Acromegaly can also cause insulin resistance and diabetes, heart problems or heart failure, or arthritis, and it increases the risk of developing benign, nonmalignant tumors.

People with acromegaly may have symptoms due to the pituitary tumor itself. Large pituitary tumors can cause headaches and change in vision (especially loss of peripheral vision, the ability to see to the sides). In addition, pituitary tumors may disrupt the normal production of hormones from the pituitary and cause symptoms related to hormone deficiencies, such as fatigue, decreased energy, lack of menstruation and low libido.

Is there a test for acromegaly?

The single best test for diagnosing acromegaly is insulin-like growth factor-1 (IGF-1) level, which is a simple blood test that can be done at any time during the day and is increased in people with acromegaly. A growth hormone level can also be checked, but growth hormone levels vary widely throughout the day based on food intake, exercise and sleep. If there is evidence of acromegaly based on elevated IGF-1 and growth hormone levels and symptoms, then an MRI scan of the brain should be done to evaluate the pituitary gland, specifically to look for a pituitary tumor. Sometimes the diagnosis of acromegaly is made when an MRI done for another reason shows a pituitary tumor.

How is acromegaly treated?

First-line therapy for acromegaly is generally surgery. Surgery is performed under general anesthesia and is done by making a small incision into the nasal cavity into an area called the sinuses. This allows easy access to the pituitary gland using a special device called an endoscope. The surgery is usually performed by both a neurosurgeon (brain surgeon), who operates directly on the pituitary gland, as well as an otorhinolaryngologist [ot-o-ri-no-lar-en-gal-ejest] (ear, nose, and throat surgeon), who operates on the back of the nasal passage. The surgery usually requires a two-to-three-day hospital stay if there are no complications. Complications of the surgery are rare when done by an experienced pituitary surgeon, but can include leakage of spinal fluid from the nose, meningitis (an infection of the covering of the brain) and hormone deficiencies.

If acromegaly is not cured by surgery or if someone is not a candidate for surgery, other treatment options include radiation and medication. The goal of radiation is to decrease tumor size and decrease growth hormone production. Since the effects of radiation therapy take time to work (sometimes up to 10 years), people are often treated with medication in addition to radiation. Some people may also require medical therapy because they are not candidates for radiation therapy due to the location of their tumor.

Medical therapy is generally administered by an endocrinologist [en-do-kri-nol-o-jist] (hormone doctor) who will monitor the effects of treatment over time. The medications include lanreotide [lan-REE-oh-tide], octreotide [ok-TREE-of-tide], pegvisomant [peg-VEEso-mant] and cabergoline [ca-BER-goe-leen]. Lanreotide and octreotide are somatostatin analogues and are taken as a shot and decrease the release of growth hormone from the tumor. Pegvisomant is a growth hormone receptor antagonist that is also taken as a shot and blocks the effects of growth hormone on the body. Cabergoline is taken as a pill and has a similar mechanism of action as lanreotide and octreotide medication, but is less effective at decreasing growth hormone production. The choice of medication depends on the specific individual situation and how effective each treatment is for the patient. Sometimes, more than one medication is required.

Could the tumor come back after surgery?

All patients, regardless of which treatment is used, need lifelong monitoring, as acromegaly can recur. Sometimes patients who are not initially cured by surgery will require a second surgery to decrease the tumor size and to control symptoms. It is very important that there is continued follow-up both with an experienced endocrinologist and a neurosurgeon who can monitor IGF-1 and growth hormone levels and follow changes on brain MRI.

Dr. C. Rachel Kilpatrick is currently a Fellow in Endocrinology, Diabetes and Metabolism at Washington University School of Medicine in St Louis, Missouri. She is an active member of the American Association of Clinical Endocrinologists and the American Diabetes Association. Upon completion of her fellowship in June of 2014, she will begin a practice in general endocrinology in Fayetteville, Arkansas.

Dr. Julie M Silverstein is a board-certified Endocrinologist and Assistant Professor of Medicine and Neurological surgery in the Division of Endocrinology, Metabolism and Lipid Research at Washington University School of Medicine in St. Louis, MO. She specializes in pituitary tumors and related disorders.