Doctor's Notes on Acromegaly
Acromegaly is a serious condition that occurs when the body produces abnormally high levels of growth hormones, the main hormone being produced by the pituitary gland. Signs and symptoms occur very slowly over time and in many people, some of the changes include enlargement of jaw and other facial bones, overgrowth of bone and cartilage in the joints causing arthritis, back pain with curvature the spine, swelling of the face, lips and tongue, sleep apnea and thick skin. Other signs and symptoms such as nerve entrapments like carpal tunnel syndrome occur. Body organs such as the heart, thyroid, liver and kidneys can become enlarged. In many individuals, the symptoms and signs develop so slowly that they are not noticed for years or even decades. It can occur in children (termed gigantism); most notable signs and symptoms in children are the abnormal growth of the legs and arms that makes the child unusually tall.Causes of acromegaly are the production of abnormally high amounts of hormones that control growth; in most individuals with acromegaly, the hormone overproduction is due to a benign tumor in the pituitary gland called an adenoma.
Some adenomas are aggressive, growing quickly. In these cases, the signs and symptoms of acromegaly tend to develop fairly quickly. Others grow more slowly, causing very gradual onset of symptoms. In these cases, symptoms might appear several years before the disease is diagnosed.
Symptoms can be divided into 2 groups: those that are effects of the tumor pressing on surrounding tissues and those caused by excess growth hormone and IGF-1 in the blood.
Symptoms due to pressure on surrounding tissues depend on the size of the tumor.
- Headaches and partial loss of vision are the most common symptoms.
- Partial loss of vision may occur in one or both eyes.
- Pituitary tumors also can damagethe pituitary gland itself, disrupting hormone production. The resulting hormone imbalances are responsible for symptoms such as impotence, low sex drive, and changes in the menstrual cycle.
Symptoms due to excess growth hormone or IGF-I vary widely.
- Increase in ring size or tightness of rings (due to hand swelling, “sausage-like” fingers)
- Increase in shoe size (due to foot swelling)
- Increased sweating
- Coarsening or thickening of facial features, especially the nose
- Increased prominence of jaw and/or forehead
- Thickened skin, especially on palms of hands or soles of feet
- Oily skin or acne
- Swelling of tongue
- Thickening or swelling of the neck (due to goiter)
- Arthritis (pain, swelling, or stiffness in any joint)
- Difficulty breathing during sleep (sleep apnea), causing poor sleep and excessive sleepiness during the day
- Pain, numbness, tingling, or weakness in hands and wrists (carpal tunnel syndrome)
- New overbite, underbite, or spreading out of teeth
- Large numbers of skin tags
Hormones are chemicals that control important body functions such as metabolism, growth and development, and reproduction. Growth hormone, like a number of hormones, is produced by the pituitary gland. It is one in a series of hormones that control tissue growth.
- The hypothalamus, a part of the brain, produces growth hormone-releasing hormone (GHRH). GHRH stimulates the pituitary to produce growth hormone and release it into the bloodstream.
- The hypothalamus produces another hormone called somatostatin that stops secretion of growth hormone.
- Growth hormone in the bloodstream stimulates the liver to produce another hormone called insulin-like growth factor 1 (IGF-1).
- IGF-1, in turn, promotes growth of bone and other tissues.
- Normally, levels of GHRH, growth hormone, somatostatin, and IGF-1 are tightly controlled by each other in a natural “feedback loop.” This feedback loop regulates supply of these hormones in the body. For example, a high level of IGF-1 in the blood suppresses secretion of GHRH and growth hormone in healthy people. Disruption of this and other similar hormone feedback loops causes many different medical problems, referred to as endocrine disorders.
- Levels of growth hormone and related hormones also are affected by sleep, exercise, stress, food intake, and blood sugar levels.
Excess growth hormone and IGF-1 in the blood cause most of the physical problems in acromegaly.
- Too much IGF-1 causes the bone growth that leads to changes in physical appearance and function.
- Itcauses thickening of soft tissues such as skin, tongue, and muscles. Enlargement of the tongue can lead to breathing problems and sleep apnea. Overgrowth of muscles can entrap nerves, causing pain syndromes such as carpal tunnel syndrome.
- Excess IGF-1 causes enlargement of organs such as the heart, which can result in heart failure and rhythm disorders.
- Excess growth hormone changes the way the body processes sugar and fats. This can cause diabetes and high levels of fats such as triglycerides in the blood. This in turn can lead to atherosclerosis and heart disease.
In most cases of acromegaly, the excess growth hormone is produced by a tumor of the pituitary gland called adenoma.
- Secretion of growth hormone by a pituitary tumor is not controlled by the feedback loop. The end result is an excess of IGF-1, which causes abnormal tissue growth.
- Many adenomas are caused by a genetic defect, but we do not know what causes the defect. These tumors do not seem to run in families.
- Adenomas are benign tumors, which means that they do not spread to other parts of the body.
- They can, however, grow to considerable size and cause problems by pressing on and invading surrounding tissues.
The remaining cases of acromegaly are caused by other types of tumors that secrete growth hormone or GHRH.
- These other tumors may be in the pituitary gland or elsewhere in the body.
- Acromegaly caused by excess growth hormone and acromegaly caused by excess GHRH have the same signs and symptoms.
It's the golden rule of joint health: The more you move, the less stiffness you'll have. Whether you're reading, working, or watching TV, change positions often. Take breaks from your desk or your chair and get active.
Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.