Find definitions for thousands of medical terms, treatments, and tests -- even health-related abbreviations, prefixes, and suffixes.
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.
February 25, 2013
Catherine D. Serio, PhD - Behavioral Health & 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
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
August 17, 2012
Anne C. Poinier, MD - Internal Medicine & E. Gregory Thompson, MD - Internal Medicine
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
The different types of echocardiograms are:
December 9, 2011
Rakesh K. Pai, MD, FACC - Cardiology, Electrophysiology & George Philippides, MD - Cardiology
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.
March 7, 2012
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.
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.
June 16, 2011
E. Gregory Thompson, MD - Internal Medicine & Brian D. O'Brien, MD - Internal Medicine
Eating disorders are conditions that cause a person to have
unhealthy thoughts and behaviors related to food and body image.
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.
August 25, 2011
Adam Husney, MD, MD - Family Medicine & W. Stewart Agras, MD - Psychiatry
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
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
November 29, 2011
E. Gregory Thompson, MD - Internal Medicine & Ken Y. Yoneda, MD - Pulmonology
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.
October 9, 2012
Susan C. Kim, MD - Pediatrics & Steven C. Schachter, MD - Neurology
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.
June 1, 2011
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
March 22, 2011
Sarah Marshall, MD - Family Medicine & Femi Olatunbosun, MB, FRCSC - Obstetrics and Gynecology
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.
November 27, 2012
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
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).
July 7, 2011
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
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
April 8, 2011
E. Gregory Thompson, MD - Internal Medicine & Jerome B. Simon, MD, FRCPC, FACP - Gastroenterology
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).
April 26, 2012
Anne C. Poinier, MD - Internal Medicine & Carla J. Herman, MD, MPH - Geriatric Medicine
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
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
March 9, 2011
E. Gregory Thompson, MD - Internal Medicine & W. David Colby IV, MSc, MD, FRCPC - Infectious Disease
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
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
December 21, 2012
Adam Husney, MD - Family Medicine & Arden Christen, DDS, MSD, MA, FACD - Dentistry
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
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.
December 14, 2012
Rakesh K. Pai, MD, FACC - Cardiology, Electrophysiology & John M. Miller, MD, FACC - Cardiology, Electrophysiology
Endocrinologists are medical doctors who specialize in the
diagnosis and treatment of diseases of the endocrine glands, which regulate
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
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
The hormones estrogen and
progesterone attach to certain receptors on the breast cells to stimulate the growth of normal breast cells and some
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.
May 14, 2012
Sarah Marshall, MD - Family Medicine & Douglas A. Stewart, MD - Medical Oncology
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:
November 2, 2011
Rakesh K. Pai, MD, FACC - Cardiology, Electrophysiology & Stephen Fort, MD, MRCP, FRCPC - Interventional Cardiology
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.
February 22, 2012
E. Gregory Thompson, MD - Internal Medicine & David A. Szalay, MD - Vascular Surgery
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.
E. Gregory Thompson, MD - Internal Medicine & Christopher G. Wood, MD, FACS - Urology, Oncology
Edema is the abnormal buildup of fluid in a part of the body, which
can cause swelling and pain.
Some causes of edema include:
The treatment for edema depends on the cause.
February 1, 2012