Glossary

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

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Barbiturate medicines are used to relieve anxiety, control seizures, or produce a state that is like sleep. Barbiturates slow breathing, lower blood pressure and body temperature, and slow thought processes and reaction times.

Frequent or long-term use of barbiturates may make a person dependent on them. In the past, barbiturates were used to treat insomnia. But barbiturates are no longer recommended as sleeping aids because of the potential for dependence.

Common barbiturates include phenobarbital, pentobarbital, and secobarbital (Seconal).

Last Revised: August 26, 2011

Author: Healthwise Staff

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

Bariatric surgery helps obese people lose weight and is used only after diet and exercise has not resulted in long-term weight loss. The surgery makes the stomach area smaller, so it fills up with less food. Sometimes surgery also changes digestion, so less food is absorbed.

After surgery, the person will not be able to eat very much at one time and will get full quickly. Stomach pain, vomiting, or diarrhea may occur if the person eats too much at one time or if the person eats foods that are high in fat or sugar. Getting good nutrition is important, because less food can be eaten and in some cases less nutrition is absorbed from that food.

Last Revised: April 6, 2011

Author: Healthwise Staff

Medical Review: E. Gregory Thompson, MD - Internal Medicine & Ali Tavakkolizadeh, MD, FRCS

A barium enema, or lower gastrointestinal (GI) examination, is an X-ray examination of the large intestine (colon and rectum). The test is used to help find problems that affect the large intestine.

To make the intestine visible on an X-ray picture, the colon is filled with a white barium contrast material. The contrast material is put through a tube placed in the anus. The barium blocks X-rays, so the barium-filled colon shows up clearly on the X-ray picture.

A barium enema may be done to check for the cause of rectal bleeding or blood in the stool. The test may help find diseases such as inflammatory bowel disease and diverticulosis. A barium enema may also be used to look for colon cancer.

Last Revised: April 24, 2012

Author: Healthwise Staff

Medical Review: Adam Husney, MD - Family Medicine & Howard Schaff, MD - Diagnostic Radiology

Basal metabolic rate (BMR) is the average daily amount of energy (calories) that is used by a body when it is at rest. Heredity, height, body composition, and age determine a person's basal metabolic rate. It is also known as basal energy expenditure (BEE).

The energy in a person's BMR is used to keep body temperature normal and to power the heartbeat, breathing, and other organ functions. Your BMR uses up about two-thirds of your daily calories.

The best measure of BMR is taken when you are not digesting any food or doing any activity, usually right after waking up for the day.

Another option is to measure resting metabolic rate (RMR), also known as resting energy expenditure (REE). This is very similar to BMR, but the test can be done with fewer restrictions.

Last Revised: April 6, 2011

Author: Healthwise Staff

Medical Review: E. Gregory Thompson, MD - Internal Medicine & Ali Tavakkolizadeh, MD, FRCS

Bell's palsy is a paralysis or weakness of the muscles on one side of the face. It causes one side of the face to droop and affects not only taste but also saliva and tear production.

In most cases of Bell's palsy, the nerve that controls muscles on either side of the face is damaged by inflammation. The cause of this inflammation is not clear, but it may be linked to a viral infection.

Last Revised: July 20, 2011

Author: Healthwise Staff

Medical Review: Anne C. Poinier, MD - Internal Medicine & Colin Chalk, MD, CM, FRCPC - Neurology

Benign paroxysmal positional vertigo (BPPV) is a balance problem that makes you feel like you're spinning or tilting if you move your head a certain way. It happens when infection or inflammation keeps tiny stones in your inner ear from moving the way they should.

A vertigo attack usually lasts less than a minute. A doctor can move your head in ways that adjust the stones so they don't affect your balance. But even without treatment, the attacks will usually go away on their own in a few weeks.

Last Revised: December 19, 2012

Author: Healthwise Staff

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

Beta-blocker medicines slow the heart rate and decrease how forcefully the heart contracts, reducing the amount of oxygen the heart needs to work. Beta-blockers are often used to treat heart conditions, including high blood pressure, heart failure, and fast or irregular heart rates.

Beta-blockers are also used for other health problems such as migraine headaches and glaucoma.

Last Revised: April 26, 2012

Author: Healthwise Staff

Medical Review: Rakesh K. Pai, MD, FACC - Cardiology, Electrophysiology & Margaret Hetherington, PHM, BsC - Pharmacy

Bile acids are part of the thick liquid called bile that helps the body to digest fats. Bile is produced by the liver, stored in the gallbladder, and released into the small intestine where food is digested.

Normally, most of the bile acids used in digestion collect in the last part of the small intestine (ileum) and are returned to the gallbladder and used again. A small amount is lost in the stool and must be replaced by the liver.

Last Revised: May 11, 2012

Author: Healthwise Staff

Medical Review: John Pope, MD - Pediatrics & Chuck Norlin, MD - Pediatrics

Bilirubin is a substance produced by the breakdown of old red blood cells and hemoglobin, the protein in red blood cells that carries oxygen from the lungs to the rest of the body. Bilirubin is removed from the body through the digestive system as part of the bile from the liver.

Normally, the body is constantly making new red blood cells and breaking down old ones. The amount of bilirubin in a person's blood is usually very low. Higher-than-normal amounts of bilirubin in the blood cause a person's skin and eyes to become yellow (jaundice). A blockage in the bile duct or certain medical conditions, such as liver disease, may cause bilirubin levels to rise to an unhealthy level.

Newborns often have high amounts of bilirubin in their blood. In most cases, the baby's system will become better able to eliminate the bilirubin within days. But a baby may need medical attention if the yellowing appears to increase after the third day of life or has not decreased by the fifth day.

Last Revised: May 11, 2012

Author: Healthwise Staff

Medical Review: John Pope, MD - Pediatrics & Chuck Norlin, MD - Pediatrics

A biopsy is a sample of tissue collected from an organ or other part of the body. A biopsy can be done by cutting or scraping a small piece of the tissue or by using a needle and syringe to remove a sample, which is then examined for abnormalities, such as cancer, by a doctor trained to look at tissue samples (pathologist).

Last Revised: November 1, 2012

Author: Healthwise Staff

Medical Review: Adam Husney, MD - Family Medicine & Robert L. Cowie, MB, FCP(SA), MD, MSc, MFOM - Pulmonology

Bipolar disorder causes extreme mood swings, from very high energy (mania) to depression. Your mood may return to normal between these swings. Bipolar disorder is also called manic-depressive disorder. It often begins in the teen or early adult years, and it may run in families.

This illness can cause behavior so extreme that it's hard to work or have successful relationships. Medicines and counseling may help control the symptoms.

Last Revised: October 9, 2012

Author: Healthwise Staff

Medical Review: Patrice Burgess, MD - Family Medicine & Lisa S. Weinstock, MD - Psychiatry

A blood clot (a clump of blood) that forms in a vein and causes inflammation is called thrombophlebitis. Symptoms include pain, tenderness, warmth, and redness along the length of a vein.

A clot may form either in a vein just under the surface of the skin (superficial thrombophlebitis) or in a vein deep in the leg (deep vein thrombosis, or DVT). Clots in a vein just under the skin rarely cause serious problems because they do not travel through the bloodstream. Once this kind of blood clot has been diagnosed by a health professional, the person can often care for the symptoms safely at home.

Thrombophlebitis can occur in any vein, but it is most common in the leg veins. Clots in a deep leg vein (deep vein thrombosis) are serious because a clot can break loose and travel through the bloodstream to the lung (pulmonary embolism). Symptoms of deep vein thrombosis include swelling, pain, and possibly redness in one leg or a noticeable new difference in the size of one leg. Another symptom of deep vein thrombosis is pain when walking or when the foot is flexed upward.

Last Revised: December 28, 2011

Author: Healthwise Staff

Medical Review: E. Gregory Thompson, MD - Internal Medicine & Jeffrey S. Ginsberg, MD - Hematology

A blood culture is a test on a sample of blood to check for bacteria, a fungus, or sometimes viruses in the bloodstream. The test may be done if a doctor suspects a blood infection. A blood culture may help determine the specific organism causing an infection and select the appropriate antibiotic to treat it.

Usually a blood culture is needed only if a person is severely ill. Blood cultures are commonly done when a person has a high fever or shaking chills that mean there may be an infection of the blood.

It usually takes between 1 and 3 days to get the results of a blood culture. But a blood culture to look for a fungus or virus can take weeks.

Last Revised: August 6, 2012

Author: Healthwise Staff

Medical Review: E. Gregory Thompson, MD - Internal Medicine & Joseph O'Donnell, MD - Hematology, Oncology

Blood pressure is the force of blood inside an artery. A blood pressure reading measures the force of blood against the walls of an artery.

Blood pressure is measured by temporarily stopping the flow of blood in an artery, usually by wrapping a cuff around the upper arm and pumping air into the cuff. As the air is released from the cuff, blood begins to flow through the artery again. When the blood begins to flow, the sound of blood flowing through the artery can be heard through a stethoscope placed on the skin over the artery inside the elbow.

  • Blood pressure readings consist of an upper and lower number (such as 120 over 90 or 120/90). Blood pressure readings are measured in units called millimeters of mercury (mm Hg).
  • The reading on the gauge when blood flow is first heard is called the systolic pressure. It is the first or upper number in a blood pressure reading. Systolic pressure is the pressure of blood against the artery walls when the heart has just finished contracting or pumping.
  • The reading on the gauge when blood flow is no longer heard is the diastolic pressure. It is the second or lower number in a blood pressure reading. Diastolic pressure is the pressure of blood against the artery walls between heartbeats, when the heart is relaxed and filling with blood.
  • Blood pressure readings usually increase as a person ages and with a variety of medical conditions.

Last Revised: April 5, 2011

Author: Healthwise Staff

Medical Review: E. Gregory Thompson, MD - Internal Medicine & Robert A. Kloner, MD, PhD - Cardiology

A blood urea nitrogen (BUN) test measures the amount of nitrogen in your blood that comes from the waste product urea. Urea is formed when protein is broken down in your body. It is made in the liver and removed from your body in urine.

A BUN test is done to tell how well your kidneys are working. If your kidneys are not able to remove urea from the blood normally, your BUN level increases. Heart failure, dehydration, certain medicines, intestinal bleeding, or a diet high in protein also can increase your BUN level. Liver disease or damage can decrease your BUN level, because urea is made in the liver. A decreased BUN level can occur normally in the second or third trimester of pregnancy.

Last Revised: August 9, 2012

Author: Healthwise Staff

Medical Review: E. Gregory Thompson, MD - Internal Medicine & Michael Mallea, MD - Nephrology

Body mass index (BMI) is a number based on a person's weight and height that provides a way to estimate the effect of weight on health. The higher the BMI, the greater the risk of some diseases, including high blood pressure, coronary artery disease, stroke, osteoarthritis, some cancers, and type 2 diabetes.

To calculate exact BMI, one of the following equations is used:

  • The person's weight in pounds and height in inches: BMI = (pounds x 703) divided by (inches squared)
  • The person's weight in kilograms and height in meters: BMI = kilograms divided by (meters squared)

Last Revised: May 1, 2012

Author: Healthwise Staff

Medical Review: Anne C. Poinier, MD - Internal Medicine & Rhonda O'Brien, MS, RD, CDE - Certified Diabetes Educator

Bone marrow is soft tissue found mainly inside the long bones, vertebrae, and pelvic bones of the body. It is made up of red marrow, which produces red and white blood cells and platelets, and yellow marrow, which contains fat and connective tissue.

People are born with only red bone marrow. As a person matures, the red marrow in many of the bones is replaced by yellow marrow. By adulthood, only about half of the bone marrow is red. Red bone marrow is found mostly in the ribs, breastbone, shoulder blades, collarbones, hip bones, skull, and spine.

Last Revised: November 19, 2012

Author: Healthwise Staff

Medical Review: E. Gregory Thompson, MD - Internal Medicine & Brian Leber, MDCM, FRCPC - Hematology

Having bradycardia means that your heart beats very slowly. For most people, a heart rate of 60 to 100 beats a minute while at rest is considered normal. If your heart beats less than 60 times a minute, it is slower than normal.

Sometimes bradycardia is normal. For example, healthy young adults and well-trained athletes often have resting heart rates of less than 60 beats a minute.

Bradycardia is abnormal when the heart's normal pacemaker does not work correctly or when the normal electrical system of the heart has been damaged. Abnormal bradycardia (also called bradyarrhythmia, sick sinus syndrome, or sinus node dysfunction) is an abnormally slow heart rate that is caused by certain medical conditions—including heart disease, hypothyroidism, and electrolyte imbalances—and some medicines. In severe forms of bradycardia, the heart beats so slowly that it does not pump enough blood to meet the body's needs. This can be life-threatening.

How bradycardia is treated depends on what is causing it. Treatment also depends on the symptoms. If bradycardia does not cause symptoms, it usually is not treated. A pacemaker is often needed to restore a normal heart rate.

Last Revised: June 2, 2011

Author: Healthwise Staff

Medical Review: E. Gregory Thompson, MD - Internal Medicine & Rakesh K. Pai, MD, FACC

A brain (cerebral) aneurysm is a bulging, weak area in the wall of an artery that supplies blood to the brain. In some cases, a brain aneurysm may cause no symptoms and go unnoticed. In other cases, the brain aneurysm ruptures. This releases blood into the skull and causes a stroke.

When a brain aneurysm ruptures, the result is called a subarachnoid hemorrhage. Depending on the severity of the hemorrhage, brain damage or death may result.

The most common location for brain aneurysms is in the network of blood vessels at the base of the brain called the circle of Willis.

Last Revised: January 3, 2013

Author: Healthwise Staff

Medical Review: E. Gregory Thompson, MD - Internal Medicine & Karin M. Lindholm, DO - Neurology

The brand name (or trade name) of a medicine is the name given to the medicine by the manufacturing company. A medicine may have more than one brand name if it is made by more than one company.

Last Revised: March 9, 2012

Author: Healthwise Staff

Medical Review: E. Gregory Thompson, MD - Internal Medicine & Theresa O'Young, PharmD - Clinical Pharmacy

Breast cancer happens when cells in your breast grow abnormally and out of control. The cancer cells can spread to other parts of your body.

You're more likely to get breast cancer as you get older. But the disease can affect women in their 40s and, rarely, women in their 30s.

Breast cancer is the most common type of cancer in women, but it can often be treated successfully if it is found early.

Last Revised: September 26, 2012

Author: Healthwise Staff

Medical Review: Adam Husney, MD - Family Medicine

Bronchodilators are medicines that relax (dilate) the airways of the lungs (bronchial tubes). This makes it easier for a person to breathe in more air.

Bronchodilators are usually given through an inhaler, which makes a fine mist that the person breathes through the mouth and into his or her lungs. Inhaled bronchodilators are preferred for treating respiratory problems, such as asthma, because they cause few side effects and are effective.

Bronchodilators are sometimes given in pill form or as an injection under the skin for a person who cannot use an inhaler.

Last Revised: February 13, 2011

Author: Healthwise Staff

Medical Review: E. Gregory Thompson, MD - Internal Medicine & Rohit K Katial, MD - Allergy and Immunology

A bruit is the sound of blood flowing through a narrowed portion of an artery. The sound means that the blood flow may be partially blocked; artery blockage is most often due to atherosclerosis (hardening of the arteries).

A doctor can hear the sound by listening with a stethoscope placed over an artery, such as the carotid artery in the neck. Bruits in the carotid arteries may be a sign that a blood vessel is partially blocked, which may increase the person's risk for having a transient ischemic attack (TIA) or stroke.

Last Revised: September 19, 2011

Author: Healthwise Staff

Medical Review: E. Gregory Thompson, MD - Internal Medicine & Richard D. Zorowitz, MD - Physical Medicine and Rehabilitation