Glossary

Find definitions for thousands of medical terms, treatments, and tests -- even health-related abbreviations, prefixes, and suffixes.

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Eating disorders are conditions that cause a person to have unhealthy thoughts and behaviors related to food and body image.

Some people with eating disorders severely restrict their food intake (anorexia nervosa), while others eat excessively (binge eating disorder or compulsive overeating). They may also vomit, take laxatives, or exercise excessively to try to prevent weight gain (bulimia nervosa).

The cause of eating disorders is not clear, but experts believe that it is related to a number of physical, psychological, cultural, and social factors. Eating disorders are most common in teenage girls and young women, but they can occur at any age and in both sexes.

People who have eating disorders may develop health problems, such as dehydration and malnutrition. Eating disorders also increase a person's risk of other health problems related to a poor diet. These other health problems can include menstrual period changes, thinning of the bones (osteoporosis) and, in severe cases, heart and other organ problems.

Eating disorders are treated primarily with counseling. Sometimes medicines also are used.

Last Revised: August 25, 2011

Author: Healthwise Staff

Medical Review: Adam Husney, MD, MD - Family Medicine & W. Stewart Agras, MD - Psychiatry

An echocardiogram (echo) is a type of ultrasound examination that uses high-pitched sound waves sent through a device called a transducer to produce an image of the heart and sometimes the aorta.

An echocardiogram measures how well the heart is working by evaluating blood flow, heart valves, and heart size, thickness, shape, and muscle movement.

The different types of echocardiograms are:

  • Transthoracic echocardiogram (TTE), in which a transducer is moved over different locations on the chest or abdomen.
  • Transesophageal echocardiogram (TEE), in which the transducer is passed down the esophagus (the muscular tube that connects the throat to the stomach) to provide clearer pictures of the heart.
  • Stress echocardiogram, in which the echocardiogram is done before and after the heart is stressed by exercise or medicine.

Last Revised: December 9, 2011

Author: Healthwise Staff

Medical Review: Rakesh K. Pai, MD, FACC - Cardiology, Electrophysiology & George Philippides, MD - Cardiology

Edema is the abnormal buildup of fluid in a part of the body, which can cause swelling and pain.

Some causes of edema include:

  • Inactivity. Swelling of the ankles during a long airplane trip is an example of edema caused by inactivity.
  • Diseases such as heart failure. If the left side of the heart is damaged, it can cause fluid to build up in the lungs (pulmonary edema).
  • Blood clots that stop the flow of blood through a blood vessel. This causes blood to pool behind the clot.
  • Infection. The body often fights an infection by increasing blood flow to the area, which can result in edema.

The treatment for edema depends on the cause.

Last Revised: February 1, 2012

Author: Healthwise Staff

Medical Review: E. Gregory Thompson, MD - Internal Medicine & David A. Szalay, MD - Vascular Surgery

Ehlers-Danlos syndrome (EDS) is a group of inherited tissue disorders. This syndrome affects collagen, which plays a major role in holding together, strengthening, and providing elasticity to body cells and tissues.

Symptoms and signs of EDS include abnormally flexible, loose joints that may easily become dislocated; unusually loose, thin, stretchy (elastic) skin; and excessive fragility of the skin, blood vessels, and other body tissues and membranes.

The many types of EDS are classified using Roman numerals (EDS I to EDS XI), based upon each type's symptoms, signs, and underlying cause.

Last Revised: February 22, 2012

Author: Healthwise Staff

Medical Review: E. Gregory Thompson, MD - Internal Medicine & David A. Szalay, MD - Vascular Surgery

The ejection fraction is a measurement of the heart's efficiency and can be used to estimate the function of the left ventricle, which pumps blood to the rest of the body.

The left ventricle pumps only a fraction of the blood it contains. The ejection fraction is the amount of blood pumped divided by the amount of blood the ventricle contains. A normal ejection fraction is more than 55% of the blood volume. If the heart becomes enlarged, even if the amount of blood being pumped by the left ventricle remains the same, the relative fraction of blood being ejected decreases. For example:

  • A healthy heart with a total blood volume of 100 mL that pumps 60 mL to the aorta has an ejection fraction of 60%.
  • A heart with an enlarged left ventricle that has a total blood volume of 140 mL and pumps the same amount (60 mL) to the aorta has an ejection fraction of 43%.

Last Revised: November 2, 2011

Author: Healthwise Staff

Medical Review: Rakesh K. Pai, MD, FACC - Cardiology, Electrophysiology & Stephen Fort, MD, MRCP, FRCPC - Interventional Cardiology

Electrical cardioversion is a procedure that uses an electric current to stop the heart momentarily. This helps the heart have a normal rhythm when it resumes beating.

Usually a person is given a sedative before the procedure. Then a device called an external defibrillator—which consists of metal paddles or pads—is placed on the person's chest. The external defibrillator sends the electrical current to the heart. Doctors are prepared to help maintain a person's circulation during the procedure with medicines and other methods.

Cardioversion may be used to help the heart return to a normal rhythm after medicines have failed to do so. The procedure also may be done in emergency situations. For example, it may be done to correct a fast heart rhythm that is causing low blood pressure, chest pain, or heart failure.

Last Revised: December 14, 2012

Author: Healthwise Staff

Medical Review: Rakesh K. Pai, MD, FACC - Cardiology, Electrophysiology & John M. Miller, MD, FACC - Cardiology, Electrophysiology

An electrocardiogram (EKG, ECG) is a test that measures the electrical signals that control heart rhythm. The test measures how electrical impulses move through the heart muscle as it contracts and relaxes.

During an electrocardiogram, small pads (electrodes) are attached to the skin on the chest, arms, and legs. The electrodes are also connected to a machine that translates the electrical activity into line tracings on paper. These tracings are often analyzed by the machine and then carefully reviewed by a doctor for abnormalities.

Last Revised: March 7, 2012

Author: Healthwise Staff

Medical Review: Rakesh K. Pai, MD, FACC - Cardiology, Electrophysiology & George Philippides, MD - Cardiology

Electrolytes are minerals found naturally in the body, such as potassium, calcium, sodium, and magnesium. Electrolytes are needed to keep the body's balance of fluids at the proper level and to maintain normal functions, such as heart rhythm, muscle contraction, and brain function.

If the body's electrolytes are not in proper balance, a person may have seizures, an irregular heartbeat, muscle weakness, and other problems. Electrolyte imbalances can be caused by a variety of health conditions, such as chronic heart or kidney disease, endocrine diseases (such as problems with the adrenal, pituitary, thyroid, or parathyroid glands), eating disorders, or bone disorders. Any condition that causes the body to lose too much water (such as diarrhea, vomiting, fever, or taking medicines called diuretics) can also lead to an electrolyte imbalance.

Last Revised: June 16, 2011

Author: Healthwise Staff

Medical Review: E. Gregory Thompson, MD - Internal Medicine & Brian D. O'Brien, MD - Internal Medicine

Emergency medicine specialists, commonly called ER doctors, are medical doctors who specialize in emergency care. They can diagnose and treat many medical emergencies and can refer people to other health professionals for further treatment.

Emergency medicine specialists may further specialize in one area of medicine, such as sports medicine, or they may only treat children (pediatric emergency medicine specialists).

Emergency medicine doctors can be board-certified through the Board of Emergency Medicine, which is recognized by the American Board of Medical Specialties.

Last Revised: August 17, 2012

Author: Healthwise Staff

Medical Review: Anne C. Poinier, MD - Internal Medicine & E. Gregory Thompson, MD - Internal Medicine

Emphysema is a long-term (chronic), irreversible lung disease that occurs when the tiny air sacs in the lungs are damaged, usually as a result of long-term smoking. It causes difficulty breathing and shortness of breath that gets worse over time.

Emphysema is a form of chronic obstructive pulmonary disease (COPD).

A rare type of emphysema is caused by the lack of a substance in the lungs called alpha1-antitrypsin. This type of emphysema is usually inherited.

Last Revised: November 29, 2011

Author: Healthwise Staff

Medical Review: E. Gregory Thompson, MD - Internal Medicine & Ken Y. Yoneda, MD - Pulmonology

Endocarditis is an infection of the heart's valves or its inner lining (endocardium). This infection is caused by bacteria or, in rare cases, fungi.

For people who have certain heart conditions, such as damaged or artificial heart valves, getting endocarditis is even more dangerous. They may need to take antibiotics before certain dental and surgical procedures. The antibiotics lower the risk of getting endocarditis.

Endocarditis is usually treated with long-term antibiotics. Or, in serious cases, it is treated with surgery to replace damaged heart valves. If not treated, endocarditis can cause stroke, infection in other organs, heart failure, or kidney failure.

Last Revised: March 9, 2011

Author: Healthwise Staff

Medical Review: E. Gregory Thompson, MD - Internal Medicine & W. David Colby IV, MSc, MD, FRCPC - Infectious Disease

Endocrinologists are medical doctors who specialize in the diagnosis and treatment of diseases of the endocrine glands, which regulate hormones.

Endocrinologists are internists who have additional training in endocrinology. They often treat diabetes and thyroid disorders. They may further specialize in treating specific age groups, such as pediatric endocrinologists, who only treat children.

Endocrinologists can be board-certified through the Board of Internal Medicine, which is recognized by the American Board of Medical Specialties.

Last Revised: August 17, 2012

Author: Healthwise Staff

Medical Review: Anne C. Poinier, MD - Internal Medicine & E. Gregory Thompson, MD - Internal Medicine

Endometrial cancer means that the cells in the lining of your uterus grow abnormally and out of control. The cancer cells can spread to other parts of your body. Endometrial cancer is also called cancer of the uterus or uterine cancer. It's usually cured when found early.

Last Revised: November 27, 2012

Author: Healthwise Staff

Medical Review: Sarah Marshall, MD - Family Medicine & Ross Berkowitz, MD - Obstetrics and Gynecology

Endometrial hyperplasia is an abnormal thickening of the uterine lining (endometrium) that causes heavy vaginal bleeding and menstrual pain. If endometrial hyperplasia is not treated, it may progress to endometrial cancer.

Treatment for endometrial hyperplasia includes taking hormones, having a dilation and curettage (D&C), having a procedure to destroy the inner lining of the uterus (endometrial ablation), or having surgery to remove the uterus (hysterectomy).

Last Revised: July 7, 2011

Author: Healthwise Staff

Medical Review: Adam Husney, MD - Family Medicine & Kirtly Jones, MD - Obstetrics and Gynecology

An enzyme is a protein produced by the body to speed up a specific chemical reaction in the body. The body produces many different kinds of enzymes for many different body processes, such as digestion and blood clotting.

Some inherited diseases are caused by problems with the production of certain enzymes. Doctors may measure the levels of certain enzymes in a person's blood to help diagnose certain types of disease, such as liver problems.

Last Revised: April 8, 2011

Author: Healthwise Staff

Medical Review: E. Gregory Thompson, MD - Internal Medicine & Jerome B. Simon, MD, FRCPC, FACP - Gastroenterology

Epilepsy is a disorder that causes repeated seizures. Seizures may cause problems with muscle control, movement, speech, vision, or awareness. They usually don't last very long, but they can be scary.

Most people are able to control their seizures with medicines. Some people outgrow epilepsy and no longer have seizures.

Last Revised: October 9, 2012

Author: Healthwise Staff

Medical Review: Susan C. Kim, MD - Pediatrics & Steven C. Schachter, MD - Neurology

An erection problem means that a man can't get or keep an erection that is firm enough for him to have sex. Erection problems are also called erectile dysfunction or impotence.

Erection problems can happen at any age but are more common in men with other health problems, like diabetes. Having an occasional episode is considered normal and usually isn't a serious problem.

Last Revised: October 9, 2012

Author: Healthwise Staff

Medical Review: E. Gregory Thompson, MD - Internal Medicine & Christopher G. Wood, MD, FACS - Urology, Oncology

Esophageal cancer is a growth of abnormal cells in the esophagus, the muscular tube that connects the throat to the stomach. People who regularly use tobacco and drink alcohol increase their risk for this form of cancer.

Symptoms include difficulty swallowing and weight loss. Also, hoarseness, chest or back pain, or coughing when swallowing may occur. The person may spit up or vomit bloody mucus.

Treatment may include any combination of surgery, radiation, or chemotherapy.

Last Revised: December 21, 2012

Author: Healthwise Staff

Medical Review: Adam Husney, MD - Family Medicine & Arden Christen, DDS, MSD, MA, FACD - Dentistry

The esophagus is the muscular tube that connects the throat to the stomach. The muscles in the esophagus contract to move food and liquid from the mouth through the throat and down to the stomach.

Last Revised: June 1, 2011

Author: Healthwise Staff

Medical Review: Kathleen Romito, MD - Family Medicine & Peter J. Kahrilas, MD - Gastroenterology

Estrogen is a hormone that produces female physical traits and helps regulate a woman's menstrual cycle. In women, estrogen is produced in varying amounts throughout the menstrual cycle, mainly by the ovaries.

When a woman's estrogen levels reach a low enough point, she stops having monthly menstrual periods (menopause). This can happen as part of natural aging. Or it can happen when a woman's ovaries have been removed or have been damaged by chemotherapy or radiation. After menopause, a woman's adrenal gland and the androgen from fat cells produce low levels of estrogen.

Men have low levels of estrogen in their bodies. Overweight and obese men and women have higher estrogen levels than those with lower body fat.

Last Revised: March 22, 2011

Author: Healthwise Staff

Medical Review: Sarah Marshall, MD - Family Medicine & Femi Olatunbosun, MB, FRCSC - Obstetrics and Gynecology

Estrogen and progesterone receptor (ER/PR) tests identify whether hormones affect the way that breast cancer grows. The results of these tests help doctors decide whether to use hormone therapy to help stop the cancer from growing.

The hormones estrogen and progesterone attach to certain receptors on the breast cells to stimulate the growth of normal breast cells and some breast cancers.

Breast cancer cells that lack these receptors (ER-negative and PR-negative cancers) are much less likely to respond to treatment with such medicines as tamoxifen or aromatase inhibitors. ER/PR-positive tumors have these receptors and are more likely to respond to treatment with tamoxifen or aromatase inhibitors.

Last Revised: May 14, 2012

Author: Healthwise Staff

Medical Review: Sarah Marshall, MD - Family Medicine & Douglas A. Stewart, MD - Medical Oncology

Estrogen therapy (ET) is a treatment for women that helps replenish low estrogen levels. This therapy involves taking the hormone estrogen on a regular basis.

The body naturally produces less estrogen after menopause, when the ovaries are removed, or as a result of some other health conditions. ET can help reverse the effects of low estrogen, which may include severe menopausal symptoms, such as hot flashes and insomnia, and long-term problems, such as weak and brittle bones (osteoporosis).

Estrogen therapy is also called unopposed estrogen therapy because a second hormone (progestin) is not used along with the estrogen. Estrogen used alone can cause cancer of the lining of the uterus (endometrial cancer). For this reason, unless a woman has had her uterus removed, estrogen usually is combined with progestin; this combined therapy is called hormone therapy (HT).

Last Revised: April 26, 2012

Author: Healthwise Staff

Medical Review: Anne C. Poinier, MD - Internal Medicine & Carla J. Herman, MD, MPH - Geriatric Medicine

The quality of evidence tells us how much we can trust it and how much we can rely on it to help us make decisions. Evidence quality can be rated using four levels: high, moderate, borderline, and inconclusive.

  • High: When the quality is high, scientists are very confident that the evidence shows the real effects of the treatment or test. There is very little chance that new research will change their confidence. We can really trust the evidence.
  • Moderate: When the quality is moderate, scientists are fairly confident that the evidence shows the real effects of the treatment or test. But more research could change this. And it could show different effects of the treatment or test. Still, we can trust this evidence enough to help us make decisions about the treatment or test.
  • Borderline: This means that scientists aren't very confident about this evidence. More research is needed. We can't really trust this type of evidence. But if we're careful, we may be able to use it to make decisions about the treatment or test.
  • Inconclusive: Evidence may be inconclusive when not enough studies have been done or when the results of different studies don't agree. Or it may be that the studies were not done well enough to provide good evidence. We can't really trust this type of evidence. But sometimes it's the only evidence available.

Last Revised: February 25, 2013

Author: Healthwise Staff

Medical Review: Catherine D. Serio, PhD - Behavioral Health & Brian D. O'Brien, MD - Internal Medicine