According to the National Institute of Diabetes and Digestive and Kidney Diseases, three out of every million people have acromegaly, which is usually caused by a benign tumor in the pituitary gland that leads to the excessive secretion of growth hormone. When the excessive secretion occurs in childhood, it results in gigantism and causes long bones and tall stature. When the excess occurs after normal bone growth has stopped, the condition is called acromegaly.

The most well-known signs of acromegaly are enlarged hands and feet: It's not uncommon for a man's shoe size to increase by three sizes or for a woman to find that her wedding ring no longer fits. Still, people often go many years without being diagnosed because these changes occur so gradually. If undiagnosed and untreated, acromegaly can lead to serious health complications, such as arthritis, diabetes, hypertension, cancer and death.

Below, Larry Katznelson, MD, an assistant professor of medicine at Harvard Medical School and a physician at Massachusetts General Hospital, explains how this condition occurs and how it is best treated.

What is acromegaly?
Acromegaly is an uncommon yet chronic condition caused by an excess of a chemical called growth hormone, which—when elevated in the blood—leads to changes in the body, such as growth of the hands, the face and the feet and causes internal changes such as an enlarged heart and sleep problems and can lead to long-term risk and mortality.

What causes acromegaly?
Over 95 percent of cases of acromegaly are due to a tumor—a benign growth—of the pituitary gland. Rarely, acromegaly can be caused by growth hormone production from other parts of the body, which can include malignancies in the abdomen, but these are exceedingly rare.

What are some of the symptoms of acromegaly?
There are two main categories of problems associated with acromegaly. One category is related to the tumor itself. The pituitary gland sits in a bony, confined cavity at the base of the skull. If there's a tumor of the pituitary gland that begins to grow, it tends to grow upwards and outwards, leading to disruption of the optic nerves, which can cause a loss of vision and problems with some of the cranial nerves that can lead to changes in the function of the face.

The other class of symptoms associated with acromegaly is due to elevated levels of the growth hormone itself in the blood. And this is what can lead to the enlargement of the hands, the joints and some of the internal organs.

The joint pains may require joint replacements such as hip replacement and that can be terribly painful. Other symptoms include sleep disorders, including sleep apnea syndrome. In addition, patients can have heart disease from a thickened heart leading to shortness of breath, particularly with exercise.

So there can be a whole range of signs and symptoms with acromegaly that can be debilitating.

Is it hard to diagnose acromegaly?
Acromegaly is extremely difficult to diagnose. Patients' growth hormone levels are slowly increasing over the course of many years and the changes are often subtle. Sometimes patients see someone they haven't seen in a long time or a new physician, and that person comments on the changes, whereas patients won't see them day-to-day in the mirror.

In fact, if we look back at patients in terms of their symptoms before diagnosis, we find that patients probably had active acromegaly for at least 10 years prior to diagnosis.

What are the goals for therapy in acromegaly?
There are two major goals for the therapy. One is to reduce the tumor size in order to prevent the complications from the tumor on the brain. The second goal is to lower the growth hormone levels, because it is the growth hormone that circulates through the blood and leads to the changes in the body.

The bony changes of acromegaly, which can be very marked and disfiguring, are usually there to stay. All the soft-tissue stuff—the large hands, the large feet, the thickened heart—can regress in size with appropriate therapy.

What is the normal course of treatment for acromegaly?
The primary mode of therapy is surgery. Surgery leads to the most rapid normalization of growth hormone and decrease in tumor size. We can also use radiation therapy, usually for those patients who have residual tumors after surgery. But after surgery, most patients need therapy using medicines, and there are three main classes of medicines that we can use.

How is surgery used to treat acromegaly?
The surgery that is used for acromegaly is called transsphenoidal surgery, which means that the surgery is performed through the nose. It's a fairly benign surgery in experienced hands, and it can be very successful at decreasing tumor size and growth hormone levels.

The efficacy of surgery is really based on tumor size and location, and this is the problem with acromegaly. Often patients have had the disease for many years before it is diagnosed and the tumors often are quite large at the time of diagnosis, so surgery is successful in approximately half to two-thirds of patients. True surgical success is determined by normalization of the hormone levels.

What types of medications are used to treat acromegaly?
There are two major effects that the medicines have for the treatment of acromegaly. One is to lower the growth hormone levels to improve the signs and symptoms of acromegaly. The other very important effect is to prevent the tumors from either becoming larger or, if possible, to decrease the tumor size. The major classes of medication are somatostatin analogs and dopamine agonists.