Definition Adrenocorticotropic hormone test (also known as an ACTH test or a corticotropin test) measures pituitary gland function. Purpose The pituitary gland produces the hormone ACTH, which stimulates the outer layer of the adrenal gland (the adrenal cortex). ACTH causes the release of the hormones hydrocortisone (cortisol), aldosterone, and androgen. The most important of these hormones released is cortisol....

Definition Adrenalectomy is the surgical removal of one or both adrenal glands. The adrenal glands are paired endocrine glands—one located above each kidney—that produce hormones such as epinephrine, norepinephrine, androgens, estrogens, aldosterone, and cortisol. Adrenalectomy is usually performed by conventional (open) surgery; however, in selected patients, surgeons may use laparoscopy . With...

Definition Adrenal virilism is the development or premature development of male secondary sexual characteristics caused by male sex hormones (androgens) excessively produced by the adrenal gland. This disorder can occur before birth and can lead to sexual abnormalities in newborns. It can also occur in girls and women later in life. Description In the normal human body, there are two adrenal glands. They...

Definition of Adrenal gland cancer Adrenal gland cancers are rare cancers occuring in the endocrine tissue of the adrenals. They are characterized by overproduction of adrenal gland hormones. Description of Adrenal gland cancer Cancers of the adrenal gland are very rare. The adrenal gland is a hormone producing endocrine gland with two main parts, the cortex and the medulla. The main hormone of the adrenal...

Adjustment disorders – Definition An adjustment disorder is a debilitating reaction, usually lasting less than six months, to a stressful event or situation. It is not the same thing as post-traumatic stress disorder (PTSD), which usually occurs in reaction to a life-threatening event and can be longer lasting. Adjustment disorders Description An adjustment disorder usually begins within three months...

Adhesions Definition Adhesions are fibrous bands of scar tissue that form between internal organs and tissues, joining them together abnormally. Adhesions  Description Adhesions are made up of blood vessels and fibroblasts— connective tissue cells. They form as a normal part of the body’s healing process and help to limit the spread of infection. However when adhesions cause the wrong tissues...

Adenovirus infections Definition Adenoviruses are DNA viruses (small infectious agents) that cause upper respiratory tract infections, conjunctivitis, and other infections in humans. Adenovirus infections Description Adenoviruses were discovered in 1953. About 47 different types have been identified since then,  and about half of them are believed to cause human diseases. Infants and children are most...

Adenoid hyperplasia Definition Adenoid hyperplasia is the overenlargement of the lymph glands located above the back of the mouth. Adenoid hyperplasia Description Located at the back of the mouth above and below the soft palate are two pairs of lymph glands. The tonsils below are clearly visible behind the back teeth; the adenoids lie just above them and are hidden from view by the palate. Together these...

Addison’s disease Definition Addison’s disease is a disorder involving disrupted functioning of the part of the adrenal gland called the cortex. This results in decreased production of two important chemicals (hormones) normally released by the adrenal cortex: cortisol and aldosterone. Addison’s disease Description The adrenals are two glands, each perched on the upper part of the two kidneys....

Definition Addiction is a persistent, compulsive dependence on a behavior or substance. The term has been partially replaced by the word dependence for substance abuse. Addiction has been extended, however, to include mood-altering behaviors or activities. Some researchers speak of two types of addictions: substance addictions (for example, alcoholism, drug abuse, and smoking); and process addictions (for...

Acute stress disorder Definition Acute stress disorder (ASD) is an anxiety disorder characterized by a cluster of dissociative and anxiety symptoms occurring within one month of a traumatic event. (Dissociation is a psychological reaction to trauma in which the mind tries to cope by ‘‘sealing off ’’ some features of the trauma from conscious awareness). Acute stress disorder Description Acute...

Definition Acute poststreptococcal glomerulonephritis(APSGN) is an inflammation of the kidney tubules (glomeruli) that filter waste products from the blood, following a streptococcal infection such as strep throat. APSGN is also called postinfectious glomerulonephritis. Description APSGN develops after certain streptococcal bacteria (group A beta-hemolytic streptococci) have infected the skin or throat. Antigens...

Acute lymphangitis Definition Acute lymphangitis is a bacterial infection in the lymphatic vessels which is characterized by painful, red streaks below the skin surface. This is a potentially serious infection which can rapidly spread to the bloodstream and be fatal. Acute lymphangitis  Description Acute lymphangitis affects a critical member of the immune system–the lymphatic system. Waste materials...

Definition Acute kidney failure occurs when illness, infection, or injury damages the kidneys. Temporarily, the kidneys cannot adequately remove fluids and wastes from the body or maintain the proper level of certain kidney-regulated chemicals in the bloodstream. Description The kidneys are the body’s natural filtration system. They perform the critical task of processing approximately 200 quarts of...

Definition Acupuncture is one of the main forms of treatment in traditional Chinese medicine. It involves the use of sharp, thin needles that are inserted in the body at very specific points. This process is believed to adjust and alter the body’s energy flow into healthier patterns, and is used to treat a wide variety of illnesses and health conditions. Description Origins The original text of Chinese...

Definition Acupressure is a form of touch therapy that utilizes the principles of Acupuncture and Chinese medicine. In acupressure, the same points on the body are used as in Acupuncture, but are stimulated with finger pressure instead of with the insertion of needles. Acupressure is used to relieve a variety of symptoms and pain. Description Origins One of the oldest text of Chinese medicine is the Huang...

Definition of Actinomycosis Actinomycosis is an infection primarily caused by the bacterium Actinomyces israelii. Infection most often occurs in the face and neck region and is characterized by the presence of a slowly enlarging, hard, red lump. Description of Actinomycosis Actinomycosis is a relatively rare infection occurring in one out of 300,000(1/300,000) people per year. It is characterized by the presence...

Definition Acromegaly is a disorder in which the abnormal release of a particular chemical from the pituitary gland in the brain causes increased growth in bone and soft tissue, as well as a variety of other disturbances throughout the body. This chemical released from the pituitary gland is called growth hormone (GH). The body’s ability to process and use nutrients like fats and sugars is also altered....

Definition Acrocyanosis is a decrease in the amount of oxygen delivered to the extremities. The hands and feet turn blue because of the lack of oxygen. Decreased blood supply to the affected areas is caused by constriction or spasm of small blood vessels. Description Acrocyanosis is a painless disorder caused by constriction or narrowing of small blood vessels in the skin of affected patients. The spasm of...

Definition An acoustic neuroma is a benign tumor involving cells of the myelin sheath that surrounds the vestibulocochlear nerve (eighth cranial nerve). Description The vestibulocochlear nerve extends from the inner ear to the brain and is made up of a vestibular branch, often called the vestibular nerve, and a cochlear branch, called the cochlear nerve. The vestibular and cochlear nerves lie next to one...

Definition Acne is a common skin disease characterized by pimples on the face, chest, and back. It occurs when the pores of the skin become clogged with oil, dead skin cells, and bacteria. Description Acne vulgaris, the medical term for common acne, is the most common skin disease. It affects nearly 17 million people in the United States. While acne can arise at any age, it usually begins at puberty and...

Definition Acid phosphatase is an enzyme found throughout the body, but primarily in the prostate gland. Like all enzymes, it is needed to trigger specific chemical reactions. Acid phosphatase testing is done to diagnose whether prostate cancer has spread to other parts of the body (metastasized), and to check the effectiveness of treatment. The test has been largely supplanted by the prostate specific antigen...

Definition Achondroplasia is the most common cause of dwarfism, or significantly abnormal short stature. Description Achondroplasia is one of a number of chondodystrophies, in which the development of cartilage, and therefore, bone is disturbed. The disorder appears in approximately one in every 10,000 births. Achondroplasia is usually diagnosed at birth, owing to the characteristic appearance of the newborn....

Definition Achalasia is a disorder of the esophagus that prevents normal swallowing. Description Achalasia affects the esophagus, the tube that carries swallowed food from the back of the throat down into the stomach. A ring of muscle called the lower esophageal sphincter encircles the esophagus just above the entrance to the stomach. This sphincter muscle is normally contracted to close the esophagus. When...

Definition Acetaminophen is a medicine used to relieve pain and reduce fever. Description This drug is available without a prescription. Acetaminophen is sold under various brand names, including Tylenol, Panadol, Aspirin Free Anacin, and Bayer Select Maximum Strength Headache Pain Relief Formula. Many multi-symptom cold, flu, and sinus medicines also contain acetaminophen. The ingredients listing on the...

Definition Abuse is defined as anything that is harmful, injurious, or offensive. Abuse also includes excessive and wrongful misuse of a substance. There are several major types of abuse: physical and sexual abuse of a child or an adult, substance abuse, elderly abuse, and emotional abuse. Description Physical abuse of a child is the infliction of injury by another person. The injuries can include punching,...

Definition An abscess is an enclosed collection of liquefied tissue, known as pus, somewhere in the body. It is the result of the body’s defensive reaction to foreign material. Description There are two types of abscesses, septic and sterile. Most abscesses are septic, which means that they are the result of an infection. Septic abscesses can occur anywhere in the body. Only a germ and the body’s...

Definition Therapeutic abortion is the intentional termination of a pregnancy before the fetus can live independently. Abortion has been a legal procedure in the United States since 1973. Purpose An abortion may be performed whenever there is some compelling reason to end a pregnancy. Women have abortions because continuing the pregnancy would cause them hardship, endanger their life or health, or because...

Definition Selective abortion, also known as selective reduction, refers to choosing to abort a fetus, typically in a multi-fetal pregnancy, to decrease the health risks to the mother in carrying and giving birth to more than one or two babies, and also to decrease the risk of complications to the remaining fetus(es). The term selective abortion also refers to choosing to abort a fetus for reasons such as the...

Definition Partial birth abortion is a method of late-term (after 20 weeks) abortion that terminates a pregnancy and results in the death and intact removal of a fetus. This procedure is most commonly referred to as intact dilatation and extraction (D & X). It occurs in a rare percentage of pregnancies. Purpose Partial birth abortion, or D&X, is performed to end a pregnancy and results in the death...

Definition Cerebral amyloid angiopathy (CAA) is also known as congophilic angiopathy or cerebrovascular amyloidosis. It is a disease of small blood vessels in the brain in which deposits of amyloid protein in the vessel walls may lead to stroke, brain hemorrhage, or dementia. Amyloid protein resembles a starch and is deposited in tissues during the course of certain chronic diseases. Description CAA may affect...

Definition Cephalosporins are medicines that kill bacteria or prevent their growth. Purpose - Cephalosporins are used to treat infections in different parts of the body—the ears, nose, throat, lungs, sinuses, and skin, for example. Physicians may prescribe these drugs to treat pneumonia, strep throat, staph infections, tonsillitis, bronchitis, and gonorrhea. These drugs will not work for colds, flu,...

Central nervous system stimulants Definition Central nervous system (CNS) stimulants are medicines that speed up physical and mental processes.  Central nervous system stimulants Purpose Central nervous system stimulants are used to treat conditions characterized by lack of adrenergic stimulation, including narcolepsy and neonatal apnea. Additionally, methylphenidate (Ritalin) and dextroamphetamine...

Definition The central nervous system, or CNS, comprises the brain, the spinal cord, and associated membranes. Under some circumstances, bacteria may enter areas of the CNS. If this occurs, abscesses or empyemas may be established. Description In general, the CNS is well defended against infection. The spine and brain are sheathed in tough, protective membranes. The outermost membrane, the dura mater, and...

Definition Central nervous system (CNS) depressants are drugs that can be used to slow down brain activity. Purpose CNS depressants may be prescribed by a physician to treat anxiety, muscle tension, pain, insomnia, acute stress reactions, panic attacks, and seizure disorders. In higher doses, some CNS depressants may be used as general anesthetics. Description Throughout history, humans have sought relief...

Definition Cellulitis is a spreading bacterial infection just below the skin surface. It is most commonly caused by Streptococcus pyogenes or Staphylococcus aureus. Description The word ‘‘cellulitis’’ actually means ‘‘inflammation of the cells.’’ Specifically, cellulitis refers to an infection of the tissue just below the skin surface.In  humans, the skin...

Definition Cell therapy is the transplantation of human or animal cells to replace or repair damaged tissue and/or cells. Purpose Cell therapy has been used successfully to rebuild damaged cartilage in joints, repair spinal cord injuries, strengthen a weakened immune system, treat autoimmune diseases such as AIDS, and help patients with neurological disorders such as Alzheimer’s disease, Parkinson’s...

Paul Niehans was born and raised in Switzerland. His father, a doctor, was dismayed when he entered the seminary, but Niehans quickly grew dissatisfied with religious life and took up medicine after all. He first studied at Bern, then completed an internship in Zurich. Niehans enlisted in the Swiss Army in 1912. When war erupted in the Balkans, Niehans set up a hospital in Belgrade, Yugoslavia. The war provided...

Celiac disease Definition Celiac disease is a disease of the digestive system that damages the small intestine and interferes with the absorption of nutrients from food. Celiac disease Description Celiac disease occurs when the body reacts abnormally to gluten, a protein found in wheat, rye, barley, and possibly oats. When someone with celiac disease eats foods containing gluten, that person’s immune...

A tremor is a repetitious, involuntary shaking movement produced by the alternate contraction of opposing groups of muscles. It usually disappears during sleep. In Parkinson's disease (paralysis agitans) there is a slow motion tremor, most noticeable when the muscles are otherwise at rest, which involves the fingers (with a "pill rolling" gesture), the forearms, the head, and the tongue. A tremor...

In tetanus (lockjaw) 'the tone of various groups of muscles is increased. Difficulty in swallowing is usually the first indication of this stiffness. Then comes spasm of the muscles that close the jaw. When this symptom appears, it should be assumed that the patient has tetanus until indicated otherwise. Typically the stiffness of the muscles extends to the neck, back, abdomen, and extremities.

What should I expect after the procedure? * The doctor will remove the catheters and apply pressure to the insertion site to prevent bleeding. * You will need to stay in bed from 1 to 6 hours after the procedure to prevent bleeding. You’ll need to keep your legs still during this time. * No stitches are needed. A small sterile dressing (bandage) will cover the insertion site. * Keep this area clean...

Where is the procedure performed? Picture of an electrophysiology lab The catheter ablation takes place in a special room called the EP (electrophysiology) lab. Will I be monitored? The nurse will connect you to several monitors that will check your heart rhythm and your body’s responses to any arrhythmias during the procedure. The nurse will constantly assess you during the procedure. How does...

What tests are performed? If you take Coumadin, the results of your INR test (a blood test to evaluate blood clotting) must be within a suitable range before the procedure can be performed. Should I take my medications? * Usually you will be instructed to stop taking Coumadin (warfarin) three days before the procedure. * Your doctor may also ask you to stop taking other medications, such as those that control...

Definition Catheter ablation of an irregular heartbeat involves having a tube (a catheter) inserted into the heart through which electrical energy is sent to either reset the heartbeat or stop the heart from beating so a mechanical pacemaker can be put in place. Description Catheter ablation involves delivering highly focused heat (or radio frequency energy) to specific areas of the heart. Radio frequency...

Definition Catecholamines is a collective term for the hormones epinephrine, norepinephrine, and dopamine. Manufactured chiefly by the chromaffin cells of the adrenal glands, these hormones are involved in readying the body for the ‘‘fight-or-flight’’ response (also known as the alarm reaction). When these hormones are released, the heart beats stronger and faster, blood pressure rises,...

Definition Catatonia is a condition marked by changes in muscle tone or activity associated with a large number of serious mental and physical illnesses. There are two distinct sets of symptoms that are characteristic of this condition. In catatonic stupor the individualexperiences a deficit of motor (movement) activity that can render him/her motionless. Catatonic excitement, or excessive movement, is associated...

In some healthy persons a loss of pigment occurs in certain sharply limited areas of the skin, including the hands and face. The involved areas look white in contrast to the surrounding areas of normally colored skin. This cosmetic defect is more noticeable, of course, in persons with dark complexions. The cause is not understood; and there is no satisfactory treatment

(See also Fainting  |  Coma.) "Shock" means a condition of collapse because of a loss of blood-vessel tone, because of insufficient volume of available blood, or because of some condition which prevents blood from entering the heart. Shock occurs after severe injury, massive loss of blood, severe dehydration, overwhelming infections, or drug toxicity. The signs of shock are extreme weakness,...