Gentle Giants: Harnessing Growth Hormone

11/13/2003

Although the pituitary gland, located at the base of the brain, is just the size of a pea, it is responsible for the production of growth hormone and for regulating a network of other hormones that are essential to the successful functioning of the entire body. Problems with this tiny gland can lead to a range of serious medical conditions, including the rare diseases acromegaly and gigantism.

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.